Effects of Fasting & Time Restricted Eating on Fat Loss & Health | Huberman Lab Podcast #41

[offbeat uplifting music] – Welcome to the Huberman Lab Podcast, where we discuss science and science-based tools for everyday life. I'm Andrew Huberman, and I'm a Professor of
Neurobiology and Ophthalmology at Stanford School of Medicine. Today, we're talking all about fasting. And anytime we're talking about fasting, we are also talking about eating, because we all need to
eat sooner or later. We're going to talk about how fasting and when we eat influences a large range of aspects of our health and wellbeing,
both physical and mental. So, well, nowadays, most people are familiar with
the term intermittent fasting, also sometimes called
time-restricted feeding. I think most people
don't really understand how that process works.

It's sort of obvious that
intermittent fasting, aka time-restricted feeding, involves eating at certain
periods of each 24-hour cycle, or maybe even not eating for
entire days, in some cases. But, if you think about it,
everybody sleeps eventually. And therefore, because people
don't eat during their sleep, almost everybody is employing some form of intermittent fasting or
time-restricted feeding. What we're going to talk about today is how particular schedules
of time restricted feeding can impact our health in different ways. And when I say different ways, I mean, we're going to talk about
how intermittent fasting, aka time-restricted feeding,
impacts weight loss, fat loss in particular, muscle maintenance, and
loss and gain, organ health, such as gut health and
liver health, the genome, the epigenome, inflammation,
sickness, recovery, and healing from sickness,
exercise, cognition, mood, and lifespan.

So we're going to cover a
tremendous amount of information. I promise to make it
all directly accessible, regardless of whether or not you have a background in biology and
metabolic science or not. I'm also going to talk
about a lot of tools. In fact, I'm going to discuss a number of tools during today's episode that actually make it such that you don't have to
follow any feeding schedule, or fasting schedule, same thing if you think about it, in any absolutely strict regimented way, meaning if you were to only
eat during an eight hour period of each day, most of the time, but then occasionally eat
across a 12 hour period of the day, in theory, that could
actually have pretty serious detrimental health effects.

And yet, there are things that you can do to attenuate those negative effects. In fact, there are things that
you can do and or take that can make it as if
you did not eat at all. And so we'll discuss what those tools are. And in many cases, for sake
of health, weight loss, and performance, making the body think that
it did not eat at all can actually be quite beneficial. So today, we're going to cover mechanism and we're going to cover tools. Before we do that, I want to highlight a particular
result that was published recently, because it
serves as a useful backbone as we wade into the
conversation about fasting.

This is a study that was published in the journal Cell Metabolism:
A Cell Press Journal, excellent journal. And the title of the paper
is "Fasting Blood Glucose as a Predictor of Mortality:
Lost in Translation". And I'll explain what
the "Lost in Translation" part means in a moment. But the basic takeaway of this study, and I should mention that the first author of the
study is Palliyaguru, PALLIYAGURU, guru, Palliyaguru, et al. The basic finding of the
study is that in humans, higher blood glucose is
associated with mortality. And in fact, if you look at blood glucose, resting blood glucose across the lifespan, what you find is as people age, resting blood glucose goes up. Now, this is very interesting, because for a long time it was thought that metabolism actually
goes down as we age.

And to some extent, that's true, but the reductions in metabolism are not nearly as robust
as we once thought that they were across the lifespan. However, unless there's something done to mitigate the increase
in blood glucose associated with the aging, almost everybody experiences a gradual, but regular increase in
resting blood glucose that predicts mortality. Now, the title, as I mentioned, is "Fasting Blood Glucose
as a Predictor of Mortality: Lost in Translation". And the reason that they
included "Lost in Translation" in the title is that what I just told you, that increases in resting blood glucose predict mortality, or
are correlated with mortality, is true for human beings and for non-human primates, monkeys. But the opposite is true in mice. And so I thought it was important to use this study as an example of where it studies in mice often, but not always, translate to humans and to non-human primates. So today, I'm going to be careful to distinguish when a study was performed in mice versus in humans, because it seems that at
least when discussing feeding, blood glucose and other aspects of diet as they relate to health and wellbeing, whether or not a study
was performed in rodents or in humans can be very important.

In this case, the results were directly
180 degrees opposite to one another. In other words, in mice, resting blood glucose went down, and was associated with mortality. So lower blood glucose
associated with mortality. Whereas in humans, higher resting blood glucose
was associated with mortality. And obviously, what we're mostly interested in is health and wellbeing of ourselves, of humans. I'm sure there are some people
out there that are intensely concerned about the health
and wellbeing of mice, which you could imagine a few rare contexts
where that's important, but obviously most of us are
interested in human health. So I'll be sure to emphasize
when studies were performed in humans versus in mice. Before we begin, I'd like to emphasize that this podcast is separate from my teaching
and research roles at Stanford. It is, however, part of my desire and
effort to bring zero cost to consumer information about science and science-related tools to the general public. In keeping with that theme, I'd like to thank the
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I hope you enjoy it. Okay, so let's talk
about feeding, fasting, health and performance.

And I want to just establish
a few foundational terms so that we're all on the same page. First of all, rather than talk about fasting
or time restricted feeding, I'm largely going to talk
about time restricted feeding, but please understand that
time restricted feeding is just one side of the coin that is a two-sided coin that includes fasting on the one hand, not eating, and time restricted
feeding on the other hand, I may occasionally say fasting, but because fasting and
eating establish different biological conditions in the body, time-restricted feeding is the term that I will use to describe the overall plan of
restricting one's eating window as it's called to a particular
phase of each 24 hour day, or in some cases two particular
days within the week. Because as you'll soon learn, there are aspects of
time restricted feeding, aka fasting, that involve
eating every other day, or eating one way for five days and then fasting for
two days, and so forth.

So I'll be very precise about
what I mean and why I mean it. But for the time being, I'm going to refer to
time restricted feeding as a way to put an umbrella
over this conversation. Second of all, I am going to emphasize a
lot of biological mechanism. If you've listened to this podcast before, you know that I always begin
with biological mechanism. I do describe tools of how to
implement those mechanisms, but I wholeheartedly believe
that knowing mechanisms and understanding how these processes work gives you tremendous flexibility and understanding, and control over the processes of your mental and physical health. Whereas if I were to just list off a menu of things to do and not
to do, those will work, but those will not give you the kind of understanding that would allow you to navigate through life, through travel, through dinners out, through
different exercise schedules, whether or not you're one age
or another age, male, female, et cetera, I'm giving you mechanisms so that you can gain more
control over the systems in your brain and body.

Everything's timestamped, so if you want to jump to the to do's, you can certainly do that, but I encourage you to hang in
there for the mechanism bit. I will make it all very clear because if you understand mechanism, you are in a true place
of power and control over your biology. If ever there was a topic
that is controversial, especially on the internet, it is that of diet and nutrition.

So I'm wading into this
with a smile and in eager anticipation of all the but but but this and but but but that, and wait, but this showed that. Here's the deal, we need to precisely define what it is that we're talking about when we talk about nutrition. I'm going to give you an example of a study that was
published a few years ago, 2018, by a colleague of mine at Stanford, Chris Gardner, he's a terrific professor of nutrition and has done a lot of important studies on
how nutrition impacts different aspects of health. This is a large-scale study. It was published in JAMA, the Journal of the American
Medical Association, one of the very top tier
journals in the area of medicine, and certainly for a paper on nutrition to show up there meant that it had to meet an exceedingly high standard. This paper, where Chris
is the first author, it's Gardner et al, 2018 JAMA, looked at weight loss
in people following one particular diet versus
another particular diet. And this was a 12 month weight loss study. So it was focused
specifically on weight loss, although they looked at some
other parameters as well.

And the basic conclusion of the study was that there was no significant difference in weight change between
people following a healthy, low fat diet versus a healthy, low carbohydrate diet with significantly more dietary fats in them. This caused a lot of ripples in the world of nutrition
and nutritional science, and certainly in the general population, because anyone that understands diet and nutrition would
immediately say, but wait, there are all sorts of
different implications of eating one type of diet, say low
carbohydrate, higher fats, versus a higher
carbohydrate, lower fat diet. And indeed there are. This study was focused specifically on fat loss and on weight loss. So as we discuss time restricted feeding, we need to be very precise about what are the effects
of time restricted feeding, and of eating in particular ways at particular times, we are
going to emphasize again, whether or not the study was
done in mice or in humans, in athletes, in men, in women, or both, but the study from Gardner and colleagues is a beautiful study, and really emphasizes that if one's main goal is
simply to lose weight, then it really does not
matter what one eats provided that the number of calories burned is higher than the number
of calories ingested.

However, anyone out there who understands a little bit of biology, or a lot of biology will agree that there are many factors that impact that calories
burned part of the equation. Some of those are obvious. So for instance, amount of exercise, type of
exercise, basal metabolic rate, how much energy one
burns just sitting there. I've talked before on this podcast about NEIT, Non Exercise
Induced Thermogenesis, where if people bounce around
a lot and fidget a lot, they can burn anywhere from
800 to 2,000 calories per day. So their quote-unquote
basal metabolic rate is actually much higher simply because they're fidgeters, whereas people who tend
to be more stationary have a lower basal
metabolic rate, on average.

There's a great science to support this. Metabolic factors and hormones are also very important. Hormones, such as thyroid hormone and insulin and growth hormone, and the sex story to hormones,
testosterone and estrogen, those levels will also
profoundly influence the calories out, the
calories burned component of the calories in, calories out equation. So if out there on the internet or in listening to a particular podcast or speaker, somebody says, this is the ideal diet, or calories in, calories out does not matter, or calories in calories out is the only thing that matters. I think it's very important to understand that there are some foundational truths, such as calories in, calories out, but that of course, hormone factors and the context in which a given diet regimen is taking place are exceedingly important.

A good example of this would be puberty at that time in life, sex steroid hormones
are changing profoundly in the body as our growth
hormone and other hormones. And much of caloric intake is directed towards protein synthesis, towards the production of muscle and bone and other tissues of the body. And that's because of changes in hormones that we call puberty. So, there's no way that we can drill into every aspect of a given feeding plan or feeding schedule that would allow us to tap into every aspect of the list that I read out before weight loss, fat loss, muscle organ, genome, epigenome, inflammation, exercise,
cognition, mood, and lifespan.

But today, we're going to be very precise about how time restricted feeding, it's very clear from both animal studies and human studies can have a very powerful
and positive impact on everything from weight loss and fat loss to various health parameters. This is a beautiful literature that's emerged mostly in
the last 10 or 15 years. And as we march into this literature, what you'll see is that there actually is a perfect diet for you on a given day.

And that perfect diet for you on a given day is contextual, meaning it depends on
what you did yesterday and what you're going to do tomorrow. So there is a perfect diet for you. And today, I'm going to arm you with the mechanisms and understanding that will allow you to define what that perfect diet is and will allow you to eat on a schedule and to eat the things that are going to best serve your goals. So let's talk about eating
and what happens when you eat, and let's talk about
fasting, or not eating, and what happens when you fast. I did an entire episode on eating and metabolism, and
hormones and other factors that impact appetite.

We don't have time to go
into all those details now, although you're welcome to
listen to that episode as well, but we can briefly describe
the overall conditions that are set in the body when we eat and when we don't eat. The key word here is conditions. If I can emphasize anything
today, it's that what you eat and when you eat it set
conditions in your body, and those conditions can
be very good for you, or very bad for you,
depending on when you eat. In fact, when you eat is as
important as what you eat. I'll repeat that, when you eat is as important as what you eat, at least as it relates
to health parameters, in particular, liver
health and mental health. Some simple rules about eating. First of all, when you eat,
typically your blood glucose, your blood sugar, will go up. Also, insulin levels will go up. Insulin is a hormone that's involved in mobilizing glucose
from the bloodstream. How much your glucose and insulin go up depends on what you eat
and how much you eat. In general, simple sugars,
including fructose from fruit, but also sucrose and glucose, and simple sugars will raise your insulin and blood glucose more
than complex carbohydrates.

Things like grains, and breads,
and pastas, and so forth, and grains, and breads, and
pastas, and so forth will raise your blood glucose more
than fibrous carbohydrates, like lettuce, and broccoli,
and things of that sort. Protein has a somewhat moderate or modest impact on insulin and glucose, and fat has the lowest impact on raising your blood
glucose and blood insulin. So what you eat will
impact how steep a rise in blood glucose and insulin takes place. And there are a number of factors that are related to your individual health that will also dictate how steep and how high that rise in
glucose and insulin will be. For the time being, I'm leaving out people who have type one diabetes. These are people that don't
manufacture their own insulin, and type two diabetes is
essentially insulin insensitivity, lack of sensitivity to insulin, which leads to high blood glucose.

But, when you eat, blood glucose goes up
and when you don't eat, blood glucose and insulin go down. The longer it's been since your last meal, the lower, typically, your blood glucose and insulin will be. And the higher, things like
GLP1, glucagon-like peptide 1, glucagon being a hormone
that's also secreted when you are in a fasted state
or a low blood glucose state.

It's involved in mobilizing
various energy sources from the body, including fat
through what we call lipolysis, also using carbohydrates, and potentially even using
muscle as a source of energy. So, that's kind of a fire hose of information about what happens when you eat and don't eat, but just think of it this way, blood sugar and insulin go up when you eat, they go down when you don't eat, and other hormones go
up when you don't eat. So there are hormones associated
with the fasted state, and there are hormones associated with the eating and
having just eaten state. Now, the most important thing to understand is that,
like everything in biology, this is a process that takes time.

So insulin and glucose go up when we eat, and it takes some period of time for them to go down, even if we stop eating, they will remain up for
some period of time, and then go back down, it takes time. This is very important, because if you look at
the scientific literature on fasting, on time-restricted feeding, it's absolutely clear
that the health benefits, not just the weight loss benefits, but that the health benefits from time-restricted feeding, occur because certain conditions are met in the brain and body
for a certain amount of time. And that gives us an anchor from which to view what eating is in terms of how it sets
conditions in the body over time.

And if that sounds overly
analytic, I promise you, this is the simplest and best way to think
about any eating schedule or any eating plan. So I think it's fair to say
that in the field of nutrition, there are a few landmark
studies that serve as really strong anchors for
building our understanding of what to eat and what not to eat and when to eat, depending on our goals. The Gardner study that I mentioned earlier is one such study, in that it says if your
goal is weight loss, it really does not matter
what foods you consume, provided that you consume a
sub-maintenance, caloric diet. However, I want to emphasize again, that sets aside issues of adherence, meaning how easy or hard it
is to adhere to a given diet. Some people find it much easier to follow a high fat,
low carbohydrate diet. Some people fall follow a different diet because it's much easier for them to follow. And some people are concerned with mental performance
and athletic performance. So that study doesn't
say there's a best diet, what it says is that what you consume is less important than the
amount of food that you consume, at least for sake of weight loss, not necessarily for sake of health.

Now, the study that I'm going to refer to next is what I would consider the second major pillar
of nutritional studies. This is a truly landmark study that was carried out by Satchin Panda, who is a professor at the Salk Institute of Biological Studies in San Diego, an absolutely phenomenal institution, and an absolutely phenomenal researcher. I've known Satchin for a number of years, and I want to emphasize
that the current literature on intermittent fasting and time restricted feeding can largely be attributed to Satchin and the work that he's done. There are others involved too, of course. And of course, time-restricted feeding and fasting has a rich history
that goes back many hundreds, if not thousands of years
in different cultures and religions, but the science of time-restricted
feeding can really mainly be attributed to the incredible
work that Satchin has done. And I'm grateful to consider
him a friend and a colleague, and we consulted at length in
anticipation of this episode.

I also hope to have him on
as a guest in the future. The landmark paper that
came from Satchin's lab was published in 2012. This was a paper in
mice that set the basis for studies in humans that came later. And the title of this paper
is time-restricted feeding without reducing caloric intake, prevents metabolic diseases
in mice fed a high fat diet. So the title tells us a lot. It says that what's varied in this study is not what these mice ate,
it was when they ate it. And there were essentially four conditions in this study and the results
are absolutely remarkable. So I'm going to walk you
through the major results.

What they did is they gave mice access to different types of food. There were four groups, one group of mice had access
to just a normal mouse diet. It would not be a diet that
you'd be very interested in. I confess I've actually tasted mouse chow. If you work with mice at
all, you just have to do it. At least once it doesn't taste very good, it tastes like a very bland
Graham cracker cookie.

And I confessed that. I only
had the tiniest little bit, but mice like that stuff. And if you allow them to eat that stuff, what's called ad libitum
whenever they want, you just keep it in their
food. 24 hours a day, they will eat sometimes, and then they won't eat it at
other times, or in this case, they also had a condition where
they gave them mouse chow in a time restricted way, just for a certain
number of hours each day, but about eight hours, or they
gave them a high-fat diet. That was a separate group, got a high-fat diet at
any time they wanted.

So this was kind of the
carnival for mice because mice really like high fat,
highly palatable foods. And so they got a lot of
goodies and high-fat in their food. And then there was a fourth
group that had access to the high fat diet as much
as they wanted to eat, but only during a restricted
time period of each 24 hour cycle, now mice are nocturnal. Humans are what we call diurnal, actually, we're not really diurnal
we're crepuscular, which means that we're most
active in the morning and in the evening, not so much in the
afternoon, but nonetheless, everything I'm going to tell
you is true also for humans. And we know this now from human studies, one of the most important
things to take away from this study was that mice that ate
a highly palatable high-fat diet, a great tasting diet, but only during a restricted
feeding window of each 24 hour cycle maintained or lost
weight over time, whereas mice that ingested the same diet,
same amount of calories, but had access to those
calories around the clock, gained weight, became
obese and quite sick.

And as an additional second point, the mice that restricted
their feeding window to a particular portion of eight
hours of every 24 hour cycle actually showed some
improvement in important health markers. And what was even more incredible
is that mice that only ate during a particular feeding window, also experienced some reversal
of some prior negative health effects. So this study really lit up the
world and got people excited about time-restricted eating again. They use an eight hour feeding window. The story around that eight
hour feeding window is kind of interesting though.

Not many people know this
because it wasn't included in the paper, and there was no reason
to include it in the paper, not to out anybody, but it turns out that the
reason they used an eight hour feeding window and not a nine
hour or a 10 hour feeding window, is because studies of this sort
are actually quite demanding to perform and require the
constant presence of the graduate student, or post-doc there to ensure
that the food is in the cages at particular times and not in
the cages at other times. And mice are really good at hiding food. They'll even hide food in their jowls.

And so there's a lot of work
that has to be done to prepare for that eight hour feeding window. And to make sure after that
eight hour feeding window, there's all the food has been
removed from the cage and from the jowls of the mice and so forth. And it turns out that the
significant other of the graduate student and or postdoc, I won't reveal who they were running. This study forbid their significant other, the scientist from being in
the lab for periods of time, that were much longer than
the 10 or 12 hours that were required in order to ensure
this eight hour feeding window. So when we hear the eight
hour feeding windows are holy, they are not holy and later, we are going to talk about
how eating for a time that's restricted to eight hours
versus 10 hours versus 12 hours.

For instance, how that impacts various
parameters like health parameters and weight loss, et cetera. But the eight hour feeding
window was actually created because of a real world
constraint on the research and the relationship with the researcher
performing the research, not because there's anything
holy about an eight hour feeding window, now an important point about
when the feeding window falls within the 24 hour cycle, it is very important that the
feeding window fall during the more active phase of
one's day, so for humans, that's typically in the early
part of the day or the later part of the day, but not at night, put very simply, there are a lot of data now pointing to the fact that eating
during the nocturnal phase of the 24 hour cycle is very
detrimental to one's health. In fact, when we eat can either enhance
our health or can diminish our health. When we see light can enhance
our feelings of wellbeing or can diminish our feelings of wellbeing.

I've talked many times before about this, on the human lab podcast,
that during the daytime, you want to get as much sunlight
and other types of bright light in your eyes as safely possible. And then you want to avoid light
in the middle of the night. It has detrimental dopamine
lowering effects can cause depression, cortisol increases, et cetera. So when you view light is as
important as the light that you view. And when you eat is as important
as what you eat, in this study, they saw something
really interesting, which was that not only did
restricting food to a particular phase of the 24 hour cycle benefit, things like lean body mass
and fat loss and a number of health parameters that we'll
talk about in a moment, but it also anchored all the
gene systems of the body and provided a more regular stable
so-called circadian rhythm or 24 hour rhythm, you may be
surprised to learn that 80%, 80% of the genes in your
body and brain are on a 24 hour schedule. That is they change their levels
going from high to low and back to high again,
across the 24 hour cycle. And when those genes are high
at the appropriate times and low at the appropriate times, meaning their expression is
high and low at the appropriate times.

And therefore the proper RNAs
and proteins are made because DNA codes for RNA, RNA is
translated into proteins. When that happens, your health benefits, when those genes are not
expressed at the right times when they're higher or low at the
wrong times of each 24 hour cycle, that's when you get
negative health effects. This study showed that when
mice restrict their eating to an eight hour period within the
most active phase of their 24 hour cycle, many of the genes that are
associated with these so-called circadian clocks, these genes
have names like PER, BMAL, CRY1, et cetera, those so-called clock genes
underwent a very regular entrainment, a locking in to
the proper 24 hour schedule.

And while this was in mice, we now know that this
also occurs in humans, I've said before on this
podcast, and I'll say it again, that light, and when we view light is the
primary way in which these genes and the clock systems
of our body get organized or entrained, meaning matched to
the outside light dark cycle. So viewing light early in
the day and in the afternoon, and as much as possible all day, great, ideally that sunlight, avoiding
light in the middle of the night is also great.

It's great because it causes
the increases in particular genes and the decreases in
particular genes in every cell throughout your body at
the appropriate times, the second most powerful
timekeeper or zeitgeber, as it's called, is food, and when
you eat, and in this study, the results they saw
underscore this point, what they saw is that the peaks
in these clock genes became very regular. And the dips in these clock
genes became very regular. And that led to a whole
host of really important, positive health effects. Conversely, when mice ate, whenever they wanted
across the 24 hour cycle, these clock genes became
really out of whack and the negative health consequences
were the downstream result of these changes in these clock genes.

This is now also been shown
to be true for humans. So if you want to be healthy,
you want your organ health, your metabolic health to
be in trained properly. One of the most important
things you can do is to, if you lied at the appropriate
times of each 24 hour schedule and to not view
light at other times of that schedule and to eat at the
appropriate time of each 24 hour day. Now, again, there are rare instances that
we will discuss when skipping entire days or entire 24
hour cycles of eating can be beneficial. But for now we're talking
about schedules of time restricted feeding involve a window of
feeding that falls during your more active phase,
so during the daytime, putting aside people that work
shift work during the daytime is when you want to eat. And this eight hour feeding
window provided a very strong reinforcing signal that combines
with light to ensure that these genes are expressed
at the appropriate times. The short takeaway from this
is you probably want to think about and perhaps even engage
in time, restricted feeding.

So, as I mentioned earlier, when mice can eat around the
clock, bad things happen. And one of the bad things
that happens is that the liver suffers, the liver is involved
in all sorts of things, production of important hormones
and other factors related to metabolism. And when mice can eat around the clock, their livers got very sick,
fatty deposits in the liver. Other factors in the liver
essentially taken down the pathway of liver disease,
the time restricted feeding, essentially reversed that or
led in many cases to an even healthier liver conditions,
and that's based on this study, but also additional
studies also now in humans. So restricting your feeding
to a particular window, every 24 hour cycle has clearly
been shown now in mice and in humans to enhance liver
health, which is wonderful. How does it do this, well, it
happens because food intake, as I mentioned earlier, sets certain conditions in the
body that lasts for a period of time.

Anytime we eat, whether or not we are a
mouse or a human, there's a period of time that's required
for so-called digestion, but also gastric emptying and
other processes related to breaking down that food and utilizing it. And that is an active
process. It requires energy. And that process of breaking
down food involves certain cellular functions that if
they're ongoing throughout the 24 hour cycle or even extended
too far across the 24 hour cycle, meaning you're eating
across a 14 or a 16 hour, an 18 hour window, that
causes serious problems. And this is now been established
because of the fact that it increases the expression of
different proteins and genes in the body, as such as
TNF alpha, IL-6, IL-1. what are all those things? They are pro-inflammatory markers. So the reason that the liver
gets sick when you're eating too often is because inflammatory
markers are increased.

These inflammatory markers
are not inherently bad, they're there for a reason, but they are there in
order to respond to certain challenges, immune challenges, or the ingestion of food
and the breakdown of food. But then in an ideal circumstance, they are reduced in the period
in which there's no food present in the digestive
tract or in which there's very little food present in
the digestive tract. So by eating around the clock, you're making yourself sicker
by eating at restricted periods of time, each 24 hours a day, you're actually making
yourself healthier and you're activating certain processes
that can positively impact both weight, either maintenance
or loss of weight.

We'll talk about weight gain
a little later and positively impacting things like liver health. Also the expression of different
things related to brown fat, the fat that
increases your metabolism. We will return to this also
a little bit later and blood glucose regulation, so the
takeaway from this study, in fact, there are many
takeaways from the study. It's so wonderful is that liver health, bile acid metabolism, energy
expenditure inflammation, liver metabolites, many, many aspects of our health
are impacted by when we eat, not just what we eat, as we move forward, and we talk about intermittent
fasting for eight hour windows, six hour windows, 12 hour windows for all sorts
of different intents and purposes.

I want to start to establish
a foundational protocol that all of us, any of us can use in order
to maximize your particular goals. There are some absolutes
within this realm of time-restricted feeding. Here are a couple of absolutes
that you would want to consider, first of all, it pays off in the metabolic
sense and in the health sense and in the weight maintenance
or loss sense to not ingest any food in the first hour
after waking and potentially for longer, so I want to repeat that. One of the key pillars of
intermittent fasting is that for the first hour after you wake up and potentially
for longer to not ingest any food, okay, the second major pillar that's
well supported by research is that for the two and ideally
three hours prior to bedtime, you also don't ingest any food
or liquid calories for that matter.

And we will talk about what
it means to break a fast and whether or not certain liquids, even coffee and tea can
break a fast, et cetera, in a few moments, but
just as a foundation, it's very clear from the research
in humans that not eating any food or ingesting any
calories liquid or otherwise for the first 60 minutes
after waking up each day. And for the two to three
hours prior to your bedtime, that's ideal for the
parameters that we've discussed earlier, all the different things like
weight and liver health and metabolic health and so forth.

The two most common questions
about intermittent fasting are when is the ideal time
for the eating window? Is it early in the day, the middle of the day or later in the day? And how long should that eating window be? Should it be eight hours? We already heard why the
eight hour window was first established. It was because of these lab
conditions and the conditions of the particular relationship
of the graduate student involved, or should it be seven hours
or six hours or 12 hours. It turns out that there's some
general frameworks that we can follow in order to
answer these questions. As we move into this
portion of the discussion, I want to highlight a very
important reference that just came out, literally came out last week
in the journal endocrinology reviews. And the title of this review
is time-restricted eating for the prevention and management
of metabolic diseases. Although the data in this
paper go well beyond metabolic diseases, this is a paper
from Satchin Panda's lab. It's a very lengthy review
with an enormous table that's beautifully organized
that scripts out all the studies done in humans.

Well over a hundred
studies looking at time, restricted feeding in
athletes, men, women, children, diabetes, no diabetes, et cetera, with detailed references and
description of the outcomes. I've spent a lot of time with this review, even though it just came out
recently and is a absolute goldmine resource. It is also the major resource
for everything I'm about to tell you if you would like
to delve deeper into the material. So let's deal with this first
question of when is the ideal feeding window, and here again, we're thinking about a schedule
of eating that involves eating at least once every 24 hours, not two day or three day
or every other day fast. So it turns out that the
answer to the question, when is it best to eat is
actually best answered by thinking about the other side of the coin, which is when is it best to fast? So, because we are fasting during sleep, it's very clear that it's best
to extend the sleep-related fast either into the morning
or to start it in the evening.

Now this might seem kind of obvious, but it's actually not so obvious. You could place that feeding
window early in the day, middle of the day or late in the day. Let's think about what happens
when we sleep, when we sleep, our body undergoes a number
of different processes in the brain and body in order to
recover the cells and tissues. Many of you have probably
heard of autophagic, which is essentially a cleaning
up a gobbling up of dead cells and cells that are injured or sick. And this is a natural process that occurs, and it occurs mainly during sleep.

Although not only during sleep, fasting of any kind does tend to enhance autophagy. It is not the only way to
create autophagic conditions. Autophagic conditions can be
created simply by following a sub caloric diet. And there are other things
that one can do in order to trigger autophagy, but fasting
does trigger autophagy. So when we're asleep, the bad cells are getting
gobbled up and eaten. And the good cells also are
undergoing certain repair mechanisms mainly related to, or at least governed by those
circadian genes that we talked about earlier, those clock genes.

So you're already fasting when
you're asleep and how deep you are into that fast depends
on how long it was since your last meal. So if you fast early in the day, and you've been asleep
for 5, 6, 7, 8 hours, I would hope somewhere between
six and eight hours for most people is going to be beneficial. When you wake up, I mentioned earlier that you
don't want to eat for at least the first 60 minutes after waking, but were you to extend
that fasting to say, 9:00 AM 10:00 AM, 11:00 AM or even 12 noon or
later you are taking advantage of the deep, fast that
you were in during sleep. And certainly toward
the end of sleep, now, why do I say deep, fast? Well, because when we eat the clearance
of that food from our gut and the processes in our cells
and organs that are related to digestion, and the utilization of that
food takes about five to six hours, so if you eat a meal
and that meal lasts 10 minutes, 20 minutes or 30 minutes, or even an hour, and then you stop eating,
you've stopped eating, but you are not fasting at that point.

You can say you're fasting
because you're no longer putting food into your digestive tract, but you're not in a fasted state. You are not under conditions
of fasting, later, I'll talk about things that
you can do to accelerate the transition into fasting. So one thing is certain, that
you want your eating window to be tacked or attached to your
sleep based fasting in a way that makes it easier for you
to get into the fasted state for a period of time. So we can view that point
from the perspective of best, better and worst, okay? So if you are like most
people and you sleep at night, you're waking up somewhere
around 6:30, 7:00 AM, or maybe even 8:00 AM.

Let's say you were to push
your fasting window out, such that you started eating at noon, and then you stopped eating at 6:00 PM. Well, then you're not eating from
6:00 PM until let's say your bedtime is 10:00 PM, but
from 6:00 PM to 10:00 PM, your body is not yet in a fasted
state because you just ate. However, you're starting to taper into
a fastest state before sleep and then all through sleep. And until the next
morning and late morning, you are actually in a fasted state, now, most people find it very hard
to only eat in the middle of the day, so while that's best, it's ideal for sake of the fasting related improvements in health, it is not ideal.

And it's not very applicable
to most work and family and social situations. Most people eat breakfast with others and, or eat dinner with others. Some people eat lunch with
others, but in general, it's hard to restrict your
feeding window to just the absolute middle of the day, but from a purely health perspective, in a very objective way, that
would be the ideal situation. Let's imagine a different
pattern of eating where the feeding window starts in the
afternoon starts around two or even 3:00 PM. Some people don't have much
trouble or they can train themselves to get their
feeding window out to two or 3:00 PM, and then they won't
eat until 10 or 11:00 PM.

Right, if you do the math, you realize that that feeding
window is still pretty short. It still constitutes what we
would call intermittent fasting or time restricted feeding. But assuming that they go
to bed around 11:00 PM or midnight, they are not actually fasted
in sleep because for the first six hours or so of sleep, maybe five, but probably more like six hours of sleep, they're still digesting the
food that they consumed a late in the night. It does appear beneficial
to grab a hold of that sleep-related fast, meaning you don't want your
feeding window to be too close to bedtime. And that's why we came up
with this kind of foundational pillar that I discussed
with such an earlier, which is at least no eating for
the first hour after waking, but also no eating within two
to three hours prior to bed.

And because we all need to
sleep and sleep is seemingly important for our health of all kinds. You want to prioritize sleep, but because we also have to eat, then you start to think about
this and maybe it's not so good to push that feeding
window too late in the day, because when you go to sleep, you're not actually capitalizing
on the sleep related fasting. Now it's not just the case
that it's easiest to fast while in sleep, although that's true
because when we're asleep, typically we're not hungry or
looking for food or foraging for food or wanting food
or trying to resist food.

We're just sleeping. There is something special
about the fasting that occurs during sleep, because it's associated with
a number of processes that relate to the so-called lymphatic system, the movement of lymph like
fluids and other fluids through the brain, and kind of sweeping
out a garbage disposal, if you will, a clearing out of the metabolic
debris and some of the autophagy that's associated
with bad processes in the brain.

So we could do a whole episode on this, but essentially during
sleep, and in particular, during fasted states of sleep, we are undergoing a number
of automatic seller processes that clear out debris from
our brain enhance cognition, or at least offset dementia. This is now well-established
as well as a number of the same processes occurring in
the organs of our body. So what we're starting to
see here is that there are a number of constraints on
when you can eat, now, I would be remiss if I
didn't acknowledge the social constraints and the real
life constraints, some of us, because we want to eat with
our family and because our family or our significant
others eat around eight or 9:00 PM, and that's the
only time we're together, You have to eat late in the day.

And that certainly not a sin. I'm not saying that's good or bad, here we're trying to establish
if you recall, best, better, and worst. So from both a practical and
a health perspective and a purely objective view of how
intermittent fasting works and can benefit us, starting to eat each day, somewhere around 10:00 AM or around noon, and then allowing a feeding
window that goes until six or maybe 8:00 PM. That seems to me, at least based on the data
and what I understand about typical cultures, where people eat in the
daytime and in the evening, that seems to me like the kind
of schedule that will allow you to get the most out
of intermittent fasting, time-restricted feeding, but does not set you up to be
really out of sync with the social rhythms in most cultures.

If you think about it from the
perspective of say a noon to eight feeding window, what you'll find is that
you're able to eat lunch with others. If you like, or by yourself, you will be able to eat
dinner at a reasonable hour, at least in most countries,
in most cultures, eating dinner somewhere
between 6:30 and 7:00 PM is typical.

When you say a feeding
window, that goes until eight. That doesn't mean sitting
down to dinner at eight. That means your last bite of
food or ingestion of any liquid calories was at 8:00 PM. Assuming that you go to bed
somewhere between 10:00 PM and 1:00 AM that allows this tapering off, or this transition from
feeding to a fasted state, and still allows you to capitalize
on the special period of fasting that is sleep-related fasting. And again, I want to emphasize that the
fasting that occurs during sleep is vital and eating too
close to sleep will disrupt that fasting related sleep.

Now, there are a number of caveats
and details related to this, and there's an important caveat
in detail related to people that are specifically
interested in increasing or maintaining muscle mass. So first let's talk about food
volume and food type and how that relates to whether or not
you quickly or slowly enter a fasted state. Because clearly when we
talk about a feeding window, that feeding window could
include any number of different foods, it could involve
cake and ice cream, pizza, hamburgers, plants, fruit, whatever it is, or it could involve just fats
or just proteins, et cetera.

There are at least three
factors that are going to govern how quickly you transition
from ingesting food to a fasted state, remember, as you ingest your last
bite or sip of calories, that's not when the fast begins. That might be when the fastening
begins on your watch or on one of these apps that
I'll refer to later, which can help you track your
fasting and eating windows. But that's not when it actually
begins because your body is still seeing food. You're actually carrying
around food inside of you, even though you're not
putting into your mouth, you're still eating in some sense. So it should be somewhat obvious
that very large meals are going to take longer to
digest than very small meals. So that will impact how slowly
or quickly you migrate from a fed state to a fasted state. There's no way I can spell out
what exact volume of food you should ingest based on the
size of your stomach and et cetera, but you're all familiar
with being extremely full, very full, comfortably
full, somewhat full, or not feeling full and feeling hungry. So learning to gauge
food volume is important.

Also foods that include some
fats or a lot of fats will tend to slow gastric emptying time. And depending on the kind of fats, it could mean that a given
meal is digested within three hours versus five hours. And more fats might be a large
meal with a lot of fats has been, can take five or six hours. A smaller meal with less fat
is going to be digested more quickly consuming calories in
liquid form is going to mean that gastric emptying time
is going to be faster.

And then of course, there's the glucose and
the insulin aspect to it, which is that foods that lead
to big steep rises in glucose like pure sugars. Then your glucose will drop, however, if they're combined with fats, then it tends to be a more
gradual rise in glucose and it's more sustained, et cetera. Fibrous foods will also create
a more long lasting sustained release in glucose. The important thing here is
to establish a feeding window that you can comfortably manage, okay? Meaning that on average, you can obey a six hour
feeding window or an eight hour feeding window or a 10
hour feeding window. And then to place that feeding
window in a social and life context that you can manage
on a regular basis, now, there are two key points that
have been gleaned from the scientific data about this
feeding window and when to place it. And this is based on a
really important experiment that Satchin and his
colleagues have been doing.

There's a website that they
have zero-cost website called My Circadian Clock, you can go
to this website free of cost. There are a number of
important resources there, but what they've done is
they've examined the feeding behavior of thousands of people. People will take a picture of
the food they're about to eat, and it enters into their
account, maybe your account, if you create one on My
Circadian Clock, and they do this over many days or weeks, what's great about this is it establishes what's essentially called a
fetal gram a time in which people ate. And a number of important
findings have emerged from these fetal grams, across large
populations of people, different time zones with
different schedules, et cetera.

First of all, almost everybody underestimates
their feeding window. Meaning people who think that
they are on an eight hour feeding window or six hour
feeding window, when their data are analyzed, it almost is always the case
that they're actually on a feeding window that's one or even two hours
longer than they think you think, well, how could that possibly be if
people are taking their first bite at noon and they're taking
their last bite at 8:00 PM? Well, that must mean that they are
on that feeding window of eight hours. And it turns out that people cheat, but they don't cheat in
any kind of obvious way. They might have, you know, a
glass of wine after dinner, or they'll have a cup of tea
and a little bite of a cookie. And so when people are
honest and they are honest, in most cases for this experiment, what you find is that most
people's eating window is actually quite a bit longer. So in discussing this with
such in and reviewing the literature, it's clear that if you'd like
to be on a 10 hour feeding window, that you should probably
select an eight hour feeding window, because there's always a
little bit of a taper on either side of that eating window.

Very few people are extremely
strict about these eating windows. It's just hard to do in the
context of life events and social gatherings and,
and family and so forth. Okay, so as we build forward, your ideal fasting slash
time-restricted feeding schedule, we now have several different
rules that we can list out first, at least no food for the first
hour after waking up at least one hour, two, no food intake for two and ideally three hours prior to your bedtime. Three, if you want to select
an eight hour feeding window, then you should probably
focus on a six or seven hour feeding window because in reality, your feeding window is
going to be longer reality, meaning real life constraints. And if you'd like to be on
a 10 hour feeding window, you should probably select an
eight or a nine hour feeding window, because the way it plays out
is that people almost always eat outside of their
eating window, somewhat.

The other nice thing about
selecting a slightly shorter eating window than is comfortable
for you is that it takes into account that as you take
your last bite or your last sip of calories, there's
this time or taper before, which you are actually in a fasted state. And because you're eating
different things on different days, presumably some foods
leave your gut more quickly. Some things spike your insulin
and your glucose more than others. Sometimes you eat more
fat, sometimes less fat. This allows you to fall well
within the margins of the benefits of time-restricted
feeding that had been demonstrated in humans, which generally involve an
eight hour window or so. So I think this eight hour
window or six hour window is a good thing to shoot for
most people, some people, and we will discuss the exceptions, but some people truly
are exceptions to this. They just require more food. And along those lines, I just now briefly want to touch
on some of the studies that have looked at using a very
short feeding window of about four hours, nowadays, a number of people are doing
the so-called one meal per day, or are restricting their feeding
window to just four hours or six hours.

And that turns out to be an
interesting strategy and the data around it actually are
a little bit surprising. One surprising thing to leap
out of this massive literature review on time restricted feeding in humans
is that relatively short feeding windows of say four to
six hours do produce a number of positive health effects. Things like increased insulin sensitivity, which we know is good, remember type two diabetes is a reduction in
insulin sensitivity improvements in beta cell function and
the pancreas decreased blood pressure, decreased oxidative stress
decreases in things like evening appetite. So positive health effects
and psychological facts in general. However, they either produce
no change in body weight, or they tend to produce even
increases in body weight, now, of course there's variation
between individuals and between studies, but this is somewhat surprising. So the eight hour feeding window
seems to be very beneficial across almost all the
parameters that we've discussed, inflammation, weight,
loss, fat loss, et cetera, and adherence. I should mention people's ability
to stick to the diet seems quite good on this eight
hour feeding windows, but when people try and undergo
very short feeding windows of four to six hours, it seems that they are overeating
in that four to six hours, at least overeating with respect
to their metabolic needs.

Now, the contrast to this is the
so-called a one meal per day schedule, very few studies
on one meal per day, one meal per day, unless
it's a very, very long meal, a sort of feast typically would
not last four to six hours because it sort of depends
on how you define a meal. But when you look at the
very few, I should emphasize, again, very few studies
on one meal per day. People typically maintain or
lose weight on the one meal per day schedule. So what we can say is that
the seven to nine hour feeding window produces all of the
major health benefits of time-restricted feeding
as well as being pretty straightforward for most people
to adhere to on a regular basis and on a regular basis, turns out to be very important. I'll get back to that point in a moment. Whereas the four to six hour
eating window doesn't seem to serve people as well as say
a seven or eight hour eating window, simply because people are
overeating during that eating window and the one meal per day, while perhaps ideal for
certain people's schedules may actually cause people to under-eat.

And in some cases that
might be what people want. They actually want to under-eat. But when we start thinking
about in work and in sport, and when we start considering
hormone health and hormone production, fertility, that's when we can really start
to look at the seven to nine hour feeding window versus
the four to six hour feeding window versus the one meal per
day type feeding window with some different objectivity, we can start to look at it
through a different lens because it turns out that when you
place the feeding window and how long that feeding window is
actually will impact a number of other things in particular hormones, that can be very important for
a number of things related to sex and reproduction can be
related to performance at work performance in athleticism. And there are excellent studies on this.

So let's explore those now. So let's talk about some
conditions where having the feeding window early in the day would
actually be very beneficial. There was a study that was
published recently in Cell Reports, again, Cell Press Journal, excellent journal peer
reviewed, very stringent, from Aoyama, et al, so this is AOYAMA, et al. This was published just recently
in July, 2021 that looked at the distribution of protein
intake in different meals delivered either early in
the day or later in the day.

And I'm summarizing here quite a lot, but I should mention that this
study was performed in both mice and humans, same paper, mice and humans and involved
hypertrophy training, essentially increasing the
weight bearing of given limbs to try and induce hypertrophy, which is the growth of muscle tissue. It does appear that muscle
tissue is better able to undergo hypertrophy by virtue of the
fact that there's better or enhanced protein synthesis
early in the day, because of the expression of
one of these particular clock genes called BMAL, BMAL, BMAL regulates a number of
different protein synthesis pathways within muscle cells, such that eating protein early in the day, supports muscle tissue
maintenance and or growth.

And in this study, they also looked at the effects
of supplementing so-called BCAs branch chain amino acids, which is popular in bodybuilding
circles and in strength training circles and BCAs
are essential components of a number of different foods,
but can also be supplemented. The takeaway of this study
is pretty straight forward. However, the takeaway is if your main
interest is maintaining and, or building muscle, then it can be beneficial to
ingest protein early in the day, you would still want to obey this, what we're calling a kind
of foundational rule of no, not eating any food for the
first hour post waking or at least the first hour post. And the cutoff for when you
would want to eat protein would be sometime before 10:00 AM. And there I'm averaging
across a number of different situations, but in general, this BMAL expression is such
that let's say you wake up at 7:00 AM.

Your main interest is in
hypertrophy or maintenance of muscle. Then you would want to ingest
some protein sometime before 10:00 AM. But obviously if you're
interested in getting the health effects of intermittent fasting, that you wouldn't ingest any
food for at least the first 60 minutes upon waking. Now it's not as if at 10:01
AM a gate slam shut and you can't generate hypertrophy,
of course that's not the case. However, it's very interesting that
it doesn't matter when the resistance training, the load bearing exercise
occurs in the 24 hour cycle. So whether or not in other words, people are training early in
the day or they're training late in the day. It still appears that ingesting
protein early in the day favors hypertrophy or that one is better, or I should say more easily
able to access hypertrophy by way of these clock, regulated protein synthesis
mechanisms by ingesting protein early in the day, in no way, shape or form does this study say that
ingesting protein later in the day is somehow bad for you? It just emphasizes the positive
effects of ingesting protein early in the day for sake
of muscle maintenance and or hypertrophy.

So if you're somebody who is
mainly concerned with muscle maintenance and hypertrophy, then it may make sense to move
that feeding window earlier in the day. And certainly there are people
out there who are interested in muscle maintenance and hypertrophy, who aren't doing
intermittent fasting at all, and that's also perfectly fine, but this just so happens to be
an episode about intermittent fasting and time restricted feeding.

There are of course, modes of eating where one eats
small meals spread throughout the day or weights meals differently. Such that meals early in the
day are larger than later in the day or vice versa. There are a near infinite
number of ways to organize this. But if you are somebody who
is interested in deriving, the many clearly established
health effects of time-restricted feeding, and you are somebody who would
like to maintain or build muscle, then ingesting proteins in the
early part of the day would be important to you at least
on the basis of these results. And therefore that eight
hour window that we've established as more or less
ideal shifted to the later part of the day might not be
as beneficial for you. Now I can just personally say that for me. When I wake up in the morning, it's very easy for me to
not eat until noon or one or 2:00 PM.

Eating early in the day is
actually somewhat of a challenge. I discuss this point with Satchin, because we were talking about
how is it that one can move their feeding window or place
themselves onto a different schedule of intermittent fasting. And it's very clear that one
needs to provide a transition period in order for that to happen, you should allow yourself a
transition period of anywhere from one week to 10 days in
which you shift your feeding window by about an hour each day or so. And then once you establish
a feeding window that feels comfortable for you and that
you think you can maintain over time, that you simply maintain that
feeding schedule for at least 30 days, but ideally you
would do that indefinitely.

Now this turns out to be
important based on data that they've gleaned from
this My Circadian Clock massive experiment that
they've been doing, where people are entering the
times that they're feeding and, and eating. Excuse me, anytime we talk about mice, I always think about feeding because I come from a background in my lab, works on both
laboratory mice and on humans. And anytime I think about
humans, I think about eating, but of course they are the same thing.

The interesting thing to emerge
from that very large data set in humans is that when
people log their feeding times, as I mentioned before, oftentimes they think they're
eating in an eight hour window, but they are actually eating
in a much broader window. However, even for people that are very
good about restricting their feeding to a four, six
or eight hour window, if they're very strict about
the start and stop times, and when they ingest calories, one of the findings that's
really been important to note is that almost every individual
has a lot of drift in when that eating window resides
in their 24 hour period. In particular on the weekends, people are either extending or
shifting their feeding window in a way that makes it seem
that they've traveled to another time zone and are eating
according to another time zone.

And this is extremely important. As I mentioned earlier, based on the 2012 study
from Satchin's lab, where eating at a particular
phase of each 24 hour cycle can help enhance the expression
of these clock genes. If you are eating within a
very strict or semi strict feeding window, but that feeding window is
migrating around from day to day or five days a week. You're really organized
about when that falls, let's say for sake of
example, from noon to 8:00 PM, noon to 8:00 PM, Monday
Noonday PM, Tuesday, Wednesday, noon to 8:00 PM, Thursday and so forth.

But then on the Saturday, it's becoming 11:00 AM and
you're ending it early, or perhaps your starting
early in the day on Sunday, you're having brunch that
starts at nine 30 or 10, and then it's extending
out still just eight hours. But it shifting around that
can cause disruptions in the circadian clock mechanisms
that cause disruptions in the downstream effects of eating
that are taking at least two to three days to recover from. So obviously we don't want to
be overly neurotic about this stuff, but because this is an
episode about the science of intermittent fasting and
time restricted feeding, as important as how long
your feeding window is, is where that feeding window
resides in each 24 hour cycle. And perhaps even more important
than that is that it be fairly regular where that
feeding window resides. Because even if you have a
very short feeding window, if it's drifting around from day to day, that actually offsets a
number of the positive health effects of intermittent fasting.

So to really just underscore
the way that these different pieces of the biological
puzzle fit together, if you are very strict or semi
strict about your eight hour feeding window, but on the weekends that
eight hour feeding window is falling later than it normally
would during the middle of the week. It is as if you are going to bed later, even if you're going to
bed at the same time, at least from the perspective
of metabolic health, because of the way that eating
impacts these clock genes and impacts, or I should say subtracts, the sleep-related fasting that
you would normally experience if you were to finish eating
that a couple hours before bedtime, so again, we don't want to create any
overly obsessive or neurotic focus on this, I think that most, all people could benefit from
a time-restricted feeding schedule, but they should really think
hard about what they can stick to on a regular basis and
understand that they tend to underestimate the feeding window, that they actually are partaking in, and that they should place that
feeding window in a portion of the 24 hour cycle that
they can be consistent on most days, and I want to emphasize most again, because we are not laboratory mice.

We don't have a graduate student
coming in for eight hours a day because that's what their
significant other will allow them to do. And then removing the food
from our jowls and from our cages, we have access to food
pretty much, 24 hours a day, along those lines, however, there are things that we can
all do that will allow us to offset some of the drift if you will, that we experience or that we
induce in terms of when our feeding window occurs or that
the feeding window might push out a little later and then
therefore start a little later, the next day, there are things
that we can do in there, things that we can take. And so I'd like to discuss those briefly. So throughout this episode, I've more or less been alluding
to the fact that when you eat, there's some period of
time afterwards in which you're actually still eating, at least from the
perspective of metabolism, because glucose is up, insulin is up and you're
undergoing different metabolic and digestive processes that don't
really speak to you being in a fasted state, right? It's not just about when you
take your last bite or your last sip.

However, there are things that we can
do to accelerate the transition from a fed state to a fasted state. And so I'd like to discuss what those are. And I want to emphasize that
the term fed state is probably a better way to think about
it than eating or not eating because we think of eating
the verb, we're eating, we're eating, okay, we're
done eating I'm fasting now, but you're not actually fasting
you because you are fed. So we should really think about
fed and unfed states because from a seller processes
perspective and from a health perspective, that's actually what your body
and your system are paying attention to. And by now with everything
that we've laid out, I think that should be
intuitive to understand. So there's a fun and exciting
concept related to this, which is glucose clearing. You may have heard the old adage
that if you take a 20 or 30 minute walk after dinner, that it accelerates the rate
at which you digest that food.

And indeed it does, clearing
out of glucose from your system can be accomplished through
a number of different means, but light movement or
exercise does increase gastric emptying time, so for instance, if you were to eat a meal
that ended at 8:00 PM, and then plop to the couch, watch TV, or get on your computer or go to sleep, it would be five or six hours
until you have transitioned from a fed state to a fasted state. However, you can accelerate that
considerably by taking a 20 or 30 minute just light walk, it
doesn't have to be speed walking. It certainly doesn't have to be jogging, but just walking outside or moving around. So glucose clearing is an
important aspect of the transition from the fed state to the fasted state. And just a light walk can
allow you to do that, now, if you can't get outside, some people will go
through the gymnastics, literally of doing things like
air squats and pushups and things like that, and indeed, those will increase the expression
of things like glut four and things that mobilize glucose
into muscles and things of that sort, but, you know,
under most conditions, most people aren't doing
push-ups after dinner, or certainly who've had a big meal, just taking a light
walk can be beneficial.

In addition, you could consider
doing intense exercise. Now you wouldn't necessarily
want to do that immediately after eating. So let's take a look at what
high-intensity training of any kind does to blood glucose,
because in this case, it turns out that when you
do high intensity training actually has opposite
effects on blood glucose, depending on whether or not
you do it early or later in the day. So a fairly recent study looked
at so-called hit training, high intensity interval training, which of course can take
many different forms. It can take the form of
circuit training with weights. It can take the form of, you know, burpees and pushups and sprints
and all sorts of different things.

But high intensity interval
training is typically training that gets people's heart
rates up, you know, well above 70% of maximum and
then brief periods of rest and then repeating and how long
the high intensity interval training of course will also vary. There's there are a very brief, you know, six or 12 or 15 minute workouts. Some people can carry on
with high intensity interval training for up to 45
or maybe even 60 minutes in extreme cases. But when you look at the
studies that have explored high intensity interval training and
its effect on blood glucose, there are a couple of studies
that leap out, for instance, one that emphasized that blood
glucose levels will actually increase if high intensity
interval training is performed early in the day and will
decrease if high intensity interval training is
performed later in the day.

Now the purpose for this
exploration was not to explore clearance of blood glucose for
sake of intermittent fasting. It was mainly focused on athletic
performance and whether or not that was better early in
the day or later in the day, et cetera. But we can extract some
information from these studies that are beneficial for sake of
understanding glucose clearing. If you have ingested food
throughout the afternoon and evening and late in the day, and you're thinking about going
to sleep and you'd like to enter sleep in a way that
is less fed and more fasted, then engaging in high-intensity
interval training in the afternoon will lower or
evening I should say, will lower blood glucose. And in that way will help you
accelerate your transition into the fastest state provided
you don't ingest something after the high intensity
interval training. Now is the increase in blood
glucose that occurs from high intensity interval
training early in the day, is that detrimental, not necessarily.

So that oftentimes is
associated with the shuttling of nutrients to the muscles. They've just done a lot of hard work. So it's not that high intensity
interval training should not be done early in the day,
in fact, for many people, including myself training
early in the day, just for the way that my
psychology and biology works is always better for me than
training later in the day. And the other important
thing to mention is that high intensity interval training
done late in the day can be beneficial from the perspective
of glucose clearing, lowering blood glucose, and helping transition from
the fed to the fasted state in preparation for sleep.

However, if you're ingesting caffeine
or anything to engage in that high intensity interval training
in a way that prevents you from getting to sleep well, then it's going to be detrimental overall. So the reason I mentioned
this is of course, because it's nice to know that
light walks after dinner or any other meal for that matter
or high intensity interval training provided it's done
in the second half of the day can lower blood glucose and
speed the transition from fed to fasted states. But I also mentioned it because
what we are really trying to achieve when we partake in
intermittent fasting so-called time-restricted feeding is what
we're really trying to do is access unfed states or fasted states. It's not really about when
you eat and what you do. It's about extending the
duration of the fasting period as long as you can, in a way that's still compatible
with your eating, right, not the other way around. And this gets back to this
key feature of our biology, which is that what we eat
when we eat, when we exercise, when we view light, it's about setting a context
or a set of conditions in your brain and body.

So it's not so much about the
activities that you undergo. It's about the activities you
undergo and their relationship to one another over
time, and so in this way, it really beautifully highlights
the way that your biology is interacting all the
time light is setting. When you're going to be awakened, when you're going to be asleep, when you eat is going to be
determining when you're going to be awakened, when you're
going to be asleep. And when you eat is also going
to be determining when you are able to clear out debris
from your brain and body and repair the various cells
and mechanisms of your body, when you're able to reduce
those inflammatory cytokines throughout your body.

And this is really the beauty
of time research and feeding, which is, it's not really
about restricting your feeding. It's about accessing the beauty
of the fasted state, now, there are other ways to clear
out blood glucose that involve supplements or prescription drugs. These are so-called glucose
disposal agents, glucose, disposal agents, such as Metformin, which is a prescription drug or berberine, which is an over the counter
substance will lead to very dramatic reductions in blood glucose. And so they shift you from
a fed to a fasted state. And I know many people who
take berberine before eating meals that include a large
number of carbohydrates, for instance, as a way
to clear out glucose. Now I've tried berberine before. And what I can tell you is
that if you take berberine, which by the way is very
much like Metformin, its effects are almost
identical to Metformin in fact, but it's much less expensive
and it's over the counter. If you take berberine
and you have not ingested carbohydrates, many
people, including myself, experience a splitting headache, you become hypoglycemic because
it is a glucose clearing agent.

So if you're going to experiment
with things like Metformin and or berberine or similar, you want to be very cautious
that you're not clearing out blood glucose, that's already low. And the dose response for this
varies tremendously from one individual to the next. And there's a strong circadian component. So if some people react very
well to berberine early in the day, but find that later in the day, it provides extreme headaches
for some people it's the opposite. So I caution you in exploring
things like berberine and Metformin that you should
expect to experience a number of physical and psychological
effects that may work for you might be great for you, but might also not be
great for you, nowadays, there are a number of
commercially available, continuous glucose monitors, I've tried one of these, it involves putting
what's essentially a patch with a little needle
that goes into your skin, which is continuing
continually, excuse me, monitoring your blood glucose.

And you can look at it
at an app on your phone, and you can learn a lot that
way about how different foods impact the increases in
decrease in blood glucose. If you're doing experiments
with berberine or Metformin, you can see how those
impact your blood glucose. You can see how exercise
hit training or otherwise impacts blood glucose, excuse me again, it's very hard to assess blood
glucose without a continuous blood glucose monitor, and
if you're not using one, you're mainly going to be relying
on subjective things like, oh, I feel like I have low
blood sugar, or I feel shaky.

Like I have high blood sugar
or shaky cause you have low blood sugar. So I have to say that glucose
clearing agents that involve a walk or exercise moderate or
intense are going to be a lot easier to titrate and adjust
the levels of then things that you're going to take, where
you have to adjust the dosage. And then once you ingest a certain dosage, you're along for the ride, at least until the effects of
that particular compound wear off, it doesn't mean those
things don't have utility. It doesn't mean people aren't
using them because many people are, but they are potentially
a very sharp blade that is a double sided blade. So I encourage you to
approach those with caution.

If you decide to at all, it's worth thinking about what
the low blood glucose state is and why it's beneficial as
well as why it might produce headaches. And in some cases can also
adjust the effects of other hormones in the fasted state, a number of different proteins
that are expressed in cells undergo changes in their expression. We talked about this
earlier, when we are fasted, we tend to reduce the activity
of a particular protein called MTOR mammalian target of rapamycin. MTOR is very active in cells
while they are growing. So throughout development, it's also very active in
cancers of various kinds. MTOR needs to be what's
called phosphorylated. If you don't know what that
means, don't worry about it. But phosphorylation is a manner
in which certain proteins are altered so that they can
actually be functional within cells, MTOR is associated with cell
growth of all kinds healthy and unhealthy.

When MTOR is phosphorylated,
there's a marker called PS6 so phospho MTOR expressed as PM6. If this is all escaping
you, don't worry about it. Phospho MTOR and PS6
are reduced by fasting. Now, this makes sense. If you think about it, because eating and growth are
associated with each other, fasting is not necessarily anti-growth, but it is not pro
growth, and when we fast, we see increases in cells
of things like AMPK, the sirtuins, things like transcription factors like FOX-O, ATF and ketones or ketone bodies. You may have heard of the ketogenic diet. What's the point of all
this biochemistry, it's not, you just blitz you with a
bunch of cellular biology and biochemistry. It's to say that we have cell
growth pathways involving MTOR and PSX, and we have cell repair and
cell shrinkage processes that are associated with AMPK,
the so-called sirtuins, which Dr.

Davidson Claire from Harvard and others are famous for discovering and understanding
things like AMPK, these two different divergent
pathways of cell growth and cell breakdown and repair
and by breakdown, I mean, actual clearance autophagy, and repair. Those can be triggered by
being in either the fed or the fasted state. So one way I'd like you to
think about the fed state, not just eating, but having recently eaten
or the fasted state, meaning high blood glucose and, or you've recently eat eaten, or are currently eating
or drinking calories, is that when you eat or when
you don't eat, when you're fed, when you're fasted, you are either promoting
cellular growth of all kinds or you're promoting cellular repair
and clearance of all kinds.

And so, again, this is about setting conditions
in the brain and body. It's not so much about
when you eat food A or B, it leads to increases in MTOR,
anytime you eat any food, doesn't matter if it's plant-based, animal-based fat, protein,
carbohydrate, doesn't matter. You are biasing your system
towards a biochemical state of cell growth. And any time you haven't eaten
for a while or blood glucose is low, you're biasing your system
toward a state of cellar repair. And this is why people who
do not suffer from any blood glucose regulation issues
take things like berberine as glucose, disposal agents,
or take Metformin. I'm not necessarily
suggesting that you do that, but it's because those
things mimic fasting. They create situations in the
body that promote things like AMPKs, and sirtuins, and others to push your
body and your system down a route of repair, even though you might have
just eaten a meal an hour ago, along the lines of the health
benefits of intermittent fasting, there are nice data
showing improvements in the gut microbiome and in particular, in the treatment of irritable
bowel syndrome and other forms of colitis in time, restricted feeding, meaning time-restricted feeding
seems to be able to assist people with those conditions, following the general parameters
that I discussed before eight hours and so forth.

Why and how, well, by way
of intermittent fasting, impacting the expression of
these various clock genes, and because the clock genes
impact the mucosal lining the mucus lining of the gut, it appears that intermittent
fasting can reduce the amount of so-called lactobacillus
that's present in the gut. And lactose bacillus is when
in high levels is correlated with a number of different
metabolic disorders. At the same time, time-restricted feeding seems
to enhance the proliferation of some of the gut microbiota, like acetobacter and some of
the other ones that promote healthy mucosal lining, and that promote better
overall intestinal function. So these are pathways that
have now been established, and it appears that
intermittent fasting isn't just modulating these processes, but is actually having a direct
effect on the mucosal lining in a way that favors a
healthier gut microbiome. So it should come as no
surprise that many people who experience gut issues benefit
from restricting their feeding window to eight hours or so
per every 24 hour period. The other very exciting finding
about intermittent fasting is one of the major health issues these days is the proliferation
of so-called non-alcoholic fatty liver disease, 30 years or so non-alcoholic
fatty liver disease was exceedingly rare to see in the
clinic, except in alcoholics, fatty deposits in the liver are bad.

It is essentially liver disease. Nowadays children and
adults are showing up with non-alcoholic fatty liver disease. Some of these people are
obese, others are not, but it's a serious health concern. And it's growing in numbers all the time. A recent study that was
published in Cell Reports Medicine just a couple of weeks
ago, tested the hypothesis, whether or not the gut
microbiome or so-called brown fat tissue is impacting the liver health. And in particular nonalcoholic
fatty liver disease. The short takeaway from this
study is that contrary to what was previously thought,
the gut microbiome, while very important for a
number of other processes in the body doesn't seem to be related
to this non-alcoholic fatty liver disease.

This is surprising to people
or should be to those of you that have been following the
gut microbiome literature, however, brown fat, which is a healthy fat that we
have between our two scapulae and in our upper neck, it doesn't tend to be
blubbery type fat pads, but it sits deep to the skin, but creates a thermogenic effect
in the body that is helpful for reducing the amount of other fat, the type of fat that we're
more typically used to thinking about and talking about
white fat and pink fat that's subcutaneous fat around
the abdomen and so forth. Brown fat seems to have a
direct correlation with the lack of non-alcoholic fatty liver disease.

What this study showed was
that in people that have diminished concentrations of brown fat, there is a higher probability
of having non-alcoholic fatty liver disease. Now the good news is brown
fat stores can be increased. And again, this isn't going to
create blubber of brown fat. This is going to create increased
thermogenesis and actually make people leaner and brown
fat has a number of other important positive effects. Now, this is interesting because
cold exposure of anywhere from one to three minutes, two
or four times per week, or maybe even 10 minutes, two to four times per week
can increase brown fat stores. Also time-restricted feeding
has now been tied to the density of brown fat store. So time-restricted feeding also
seems to positively increase brown fat stores, probably because of the way
that brown fat stores relate to epinephrin and adrenaline, which tend to go up when we're fasted. What does this all mean? This means for sake of
liver health and for sake of reducing, or maybe preventing,
or even potentially, I want to underline potentially
reversing non-alcoholic fatty liver disease, time-restricted feeding also
appears to be beneficial.

Many people out there are
interested in optimizing their hormones, and as we mentioned earlier, insulin is a hormone and
time-restricted feeding seems to have very positive effects on
overall insulin profiles and so forth, but anytime
you mentioned hormones, people immediately seem to leap
to the sex steroid hormones, testosterone, and estrogen, because indeed they have powerful effects, both in the short-term and
the long-term in terms of our mental and physical
health and performance. There's at least one study
that's explored the effects of time, restricted eating on performance, athletic performance, immune
function, and body composition. This was a study by Mauro, et al, that was performed on elite cyclists. So I want to point that out. I was a randomized control trial, but what's really nice about
this study is that it explored a number of different hormonal
parameters in people that were using time restricted eating, or that had a more extended eating window. And they tracked
everything very carefully. And the amount of food they
were eating was actually pretty considerable, 4,800 calories,
so that's a lot of calories, but then again, they were very active and
they've measured a number of different things related
to VO2 max, et cetera, performance and overall performance
at what they did cycling is not the point that I
want to emphasize here.

Although there were some
positive effects on their performance related to
time-restricted eating, the point I want to talk about relates
to things that presumably relate to most, everybody, which are the effects on
things like glucose, thyroid, hormone, testosterone, sex,
hormone, binding globulin, which can bind up testosterone
and prevent the so-called free form of testosterone, which is the one that has most
of the actions in the brain and body. And the major takeaway
from this study was that time-restricted feeding of
the same amount of calories as the so-called control
condition, okay, same calories, but either compact throughout
the 24 hour cycle to an eight hour feeding window or allowing
them to eat over a larger feeding window did lead to
significant decreases in free testosterone. And I think a number of people
will raise their eyebrows to that and think, oh, well then maybe time-restricted
feeding is not for me. There are a number of important
considerations, of course, one is while they decrease
in free testosterone was significant.

It's also going to depend
on where people start out. So if somebody has already
lower modest levels of testosterone and it drops by 10 or 20%, that could lead them into a
state of poor performance and wellbeing, whereas if somebody
has higher testosterone, a decrease will necessarily do that. So it's important to take
that into consideration. This is why I'm always such
a fan of people doing their blood work and knowing what's
going on under the hood for them, a very change in
hormonal profile was cortisol. So-called stress, hormone cortisol, of course is also naturally
released early in the day in a healthy way to wake you
up and promote alertness, but you don't want its levels
to be too high or to have peaks in cortisol late in the day, that's actually correlated
with depression and a number of other untoured things. I would have thought that by
restricting a feeding window to a particular time each day, that these hard training
cyclists would have undergone increases in serum cortisol and in fact, the opposite was true.

They had significant reductions
in serum cortisol as a consequence of time, restricted feeding. I should mention there were
significant reductions in serum cortisol also in the control group, but not to the same extent. And the two groups did
differ significantly from one another. Now this is important because
if you just look at one hormone testosterone, you'd
say, okay, based on these data, time-restricted feeding is
reducing testosterone levels significantly, even though the number of
calories is quite high and is held constant across the study, but in fact, because cortisol is lower, it may mean that the effects
of testosterone or the reduction in testosterone is offset.

And that's because cortisol
and testosterone are always in this somewhat of a dance
in terms of cortisol, inhibiting the effects of
testosterone largely and vice versa. So it is interesting and
important to look at the total gallery of hormones. And they did look at a number of hormones. They looked at other inflammatory markers. Those were not increased. That's not surprising if you
remember back to the 2012 Satchin Panda study this
early pioneering study on time restricted feeding. They saw reductions in stress
hormones and in inflammatory markers in time, restricted feeding mice. And here, this also seems
to be the case in humans. So the takeaway is for sake
of hormone health, time restricted feeding is
compatible with quality hormone health, even in high-performing athletes, based on everything we know,
and that we've discussed, I would not suggest that
people restrict their feeding window to less than eight hours, especially if they're training
hard on a regular basis.

And it's not just athletes that should pay attention to this, when we are working very hard,
when we are psychologically stressed, when we are studying for exams, or we are in conflict with
somebody on a regular basis, that creates a stress in the body that's very similar to
that of physical training, the body and brain don't
distinguish between physical stress and mental stress, it's
all nervous system. Remember that it's just
cortisol and adrenaline. There's no special hormone
just for physical stress versus psychological stress, so again, in thinking about what sort of
feeding window will be right for you, we arrive back at this eight
hour time been that seems more or less flexible for most conditions, even high-performing elite athletes. And I would say just by logical extension, even for people that have a
lot of stress in their life. And I personally wouldn't suggest
that people who have a lot of stress in their life where
the potential for stress in their life shorten their
feeding window much shorter than eight hours, because then you would expect
that you would start to increase some of the inflammatory markers.

You would increase the stress hormones, and you would be decreasing
things like testosterone and estrogen, some of the
sex steroid hormones. So again, it's all about context
and the eight hour window, it isn't holy, but seems to be a really useful
guide to extract the great health benefits of
which there are many in, of which we've discussed from
intermittent fasting time, restricted feeding. And yet that it could still be
compatible with decent social schedules and for maintaining
hormone health in keeping with this, for women that are trying to
maintain ovulatory cycles or for couples that are
trying to get pregnant. I think it's also important
to not create a feeding window that's too short. The relationship between
feeding and body fat stores and glucose and leptin and hormones
is a well-established one.

And we can summarize it very easily here, although I've done several
episodes related to this previously on optimizing hormone health. But basically we undergo
puberty when there's enough food and there's enough body fat
that the body fat sends a signal to the brain called leptin. That's a hormone that comes
from body fat signals to the brain to turn on puberty that's puberty, but even as adults for
women that are menstruating, there needs to be sufficient
leptin signaling to the brain in order to maintain ovulation
because of the way that the brain communicates with the
pituitary and the ovaries.

Similarly for men fasting
or extreme exercise plus fasting, we now know reduces testosterone
it's impacts are not exactly clear, however,
if you reduce food intake, either in total calories
or in duration too much, you will suffer a drop in sperm
counts, fertility will drop. And this makes sense. The body is communicating to the brain, whether or not conditions
are sufficient in the body to reproduce and to presumably, and hopefully support the
health and wellbeing of those offspring. So there's a logical link
between body fat and eating and how much food is available
to you and how long it's available to you and the signals
in the brain that allow for reproductive success. There are some data that pointed
differences in the effects of intermittent fasting
for males versus females. Those data right now only come from mice, that study was published
by Satchin Panda recently, we still await the studies in humans.

Some people do not do well on
intermittent fasting either in terms of mood or hormone health. And so everyone needs to determine
for themselves whether or not having a time restricted
feeding window is good for them. How long that time-restricted
feeding window should be. I think eight hours is kind
of a nice minimum to adhere to based on everything that
we've covered today. And for some people time-restricted
feeding is not going to be compatible with
hormone health, for them, for them eating more meals
spread throughout the day, presumably smaller meals, same caloric intake is going
to be more beneficial for their hormones. This is something that is
going to be individual and is going to have to be determined
on an individual basis. However, if you're going to
try time restricted feeding, I do want to remind you that
taking a period of three to seven or ideally 10 days
to transition into it, not just going, flipping from eating to three
meals a day that span from 6:00 AM to 10:00 PM and
suddenly going to an eight hour feeding window, but rather winnowing down that
feeding window about an hour or so per day is going to allow
the hormone systems of your body, including leptin the
hypocretin orexin system, which are systems within the
body, that signal to the brain, that food is about to come
allowing those systems to adjust so that you're not
overwhelmingly hungry, irritable, and you're not throwing your
whole hormone system out of whack.

I keep coming back to this
eight hour feeding window, and I want to provide a
little more basis for it. And just to encourage that
it's not completely arbitrary. The lengthy review that
I mentioned earlier, features a number of studies
that have used this eight hour feeding window, but there's a particular study
that I'd like to highlight mainly because I don't expect
people to delve into the full reference list of the other review.

And this is a study that was carried out between Satchi Panda's lab and Krista Varady's labs. This is a collaboration. The study was carried out in
humans and is entitled effects of eight hour time restricted
feeding on body weight and metabolic disease, risk factors
in obese adults, excuse me. And this study essentially showed, I'll just read the conclusions
that an eight hour time restricted feeding produces a
mild caloric restriction and weight loss without calorie
counting, so that's key, right? These people aren't calorie
counting somehow just by adhering to an eight hour window. They are taking in fewer
calories than they're burning off and clinically it reduced blood pressure. So I mentioned the study, not because there aren't many
others involving the eight hour feeding window also in humans, but because the eight hour
feeding window has been tested in obese adults and non obese adults. And there are even a
few studies in children. So this eight hour window seems
to be a really good rule of thumb and a kind of anchor
around which we can each think about incorporating
time restricted feeding.

There are of course,
other patterns of feeding. And while some people have
engaged in longer fasts of 24 hours, 36 hours or more
alternate day fasting, meaning eating one day, not eating the next day or in
some cases eating one day and eating very few calories,
500 or 600 calories the next day has been tested. A few studies have also
looked at eating a sort of maintenance level of
calories for five days, and then taking two days
and fast clear through, or eating very few calories,
you know, 300 or 500 calories. In fact, there's a sort of a community
online of people that are exploring longer, fast for sake of trying to
offset dementia or reverse effects of dementia, thus
far, at least in my awareness, there isn't any quality clinical
peer reviewed study on that yet for sake of dementia,
although I await those studies, and if anyone's aware of them, please send me a link in the comments. But alternate day fasting has
gotten the so-called safe bill of health. This has been written up meaning
that people didn't suffer bone loss, they didn't suffer
any major detrimental effects. It does seem that it can create
significant weight loss and can help with obese individuals
that it can reduce resting blood glucose, and every other day fasting
in many cases can produce more rapid effects on weight loss
and reductions in blood glucose than time restricted feeding, however, every other day type fasting
for most people is not going to be feasible.

They're just not going to be
able to do that for a long period of time. And what hasn't really been
done is the follow-up to see whether or not people who do
every other day fasting or five days of eating followed
by two days of fasting, whether or not that leads
to a rebound in weight gain, whether or not that leads to
a rebound in blood glucose, et cetera. So for now the eight hour feeding
window and time restricted feeding seems to be the most tested, supported in animal studies and
in human studies and the one around which I think
most people should orient if they're considering getting
into time-restricted feeding, it's also sort of hard to
imagine how one could include a significant exercise schedule
or work schedule on every other day fasting.

Remember, in any study, people
are often being compensated, or at least are incentivized
in some way to adhere to the study. This is one of the major issues
that I have with any study that says that three or four
different diets are essentially equal in terms of their
ability to produce weight loss. Adherence is very different
in the outside world where you don't have a researcher
monitoring you where you're not logging all your food. Most people don't do that consistently. And we can take a little bit
of a neuroscience perspective on this to try and arrive
at what the best kind of organization of an eating plan, or if we wanted to call it a diet, we could would be for you. Many people find it easier
to just not eat for certain periods of each 24 hour cycle
than to eat smaller portions, portion control is very
hard for some people, for other people it's
manageable, but people like me.

I don't eat half the croissant. I don't think it's a real thing, it's not, it's not available to me, I should say. Now, of course I could
eat just half a croissant, but I noticed that when
I eat the croissant, because they're so delicious
that it creates a rise in blood glucose a rise in the other
hormones and chemicals that are associated with ingesting
delicious, highly palatable food. And it's actually a lot of work
for me to just eat half the croissant. There's something that's much
more thoroughly satisfying about eating the entire croissant. And actually there's something
that somewhat satisfying about not eating the croissant at all. And just knowing that later I
can eat the whole croissant. Now that's me.

Other people find that they
don't have any trouble with portion control that for them
just eating small bits of food throughout the day is what
sets them in the right psychological and physical
state for sake of work, et cetera. And I mentioned work and
mental focus because one of the aspects of fasting that have
drawn a lot of people to time restricted feeding and fasting
is the clarity of mind that people get. When first of all, they don't have to think about
when they're going to eat because they know when
their eating window begins. They also don't have to
think about regulating their behavior because they already
know when they're going to eat and when they're not going to eat. Whereas when you're restricting portions, you actually have to make
decisions all the while. You know, and I think I like
many people decide, well, you know, is that exactly half? Or could I have like another
wrong on the croissant? This kind of thing. I
don't negotiate with food. That's why I like a time
restricted feeding window.

I know I'm going to eat for, in my case, I use a 10 hour feeding window or so, and I'll eat the whole croissant. I just don't have to think about it, now, the food choices that you make
inside of that feeding window are of course also going
to be very important. Certain foods will increase blood glucose, such that you're going to
get hungrier and hungrier.

Others will maintain lower
blood glucose and will allow you to be more controlled in
the foods that you pursue. Those are all individual
considerations that are deserving of their own entire episode. But I do want to point out
that the advantage of time restricted feeding is that
it involves a lot of the decision-making in the brain. The so-called go no-go
circuitries of our basal ganglia, if you want to know this
areas that control them. Anytime we have to restrict a behavior, that's called a no-go. Anytime we engage in a
behavior, that's a go, no go behaviors require a
lot of what's called top-down control, and it's very
metabolically demanding.

And so time restricted feeding
allows you to depart from the whole no-go go negotiation that
you have to undergo when you have to restrict portions. And so I think this is a
reason why many people have gravitated towards time
restricted feeding and why for people that don't want to have
to think about all that it's just very straight forward. One of the more hot button
issues out there is whether or not given equal amounts of
caloric intake and equal amounts of activity and equal amounts
of nutrients, et cetera, whether or not restricting
food to a particular window biases, more weight loss toward fat
loss versus loss of other tissues, because of course,
when we lose weight, we can lose that from any number
of different storage sites within the body, muscle
water, glycogen, or fat.

Now this is such a hot button
issue that I almost don't want to get into it, but I'm
going to get into it anyway, because there are data
that are very interesting. This is covered in the review
that I mentioned earlier, that describes how if people
follow a time-restricted feeding schedule for long periods of time. So 60 days or longer, there's some metabolic
changes in the way that people metabolize energy that do seem
to shift the system toward more fat loss relative to burning
of other tissues when in a state of caloric restriction.

And I want to say when in a
state of caloric restriction, because there's really no
way to cheat the system, there's no way that you can
ingest far more calories than you burn or excrete, when
I say excrete, you know, I certainly don't suggest
this, but there, you know, bulimics and other people that
have eating disorders will use laxatives at a way to
eliminate food quickly from their system so it can't be converted into
fat or other forms of energy. That's a very, in that case,
it's a pathological situation, but in general calories
in versus calories out, as I mentioned earlier as this
kind of foundational element, but in states of caloric restriction, meaning sub maintenance intake, time-restricted feeding does
seem to buy us more of the energy burned to compensate
for that deficit from fat and the way it accomplishes
it is very interesting. It turns out that it drives
more fat loss by way of increasing a hepatic lipase. This is something called LAPC
hepatic means of the liver and lipase, which anytime you hear
ASC is means it's an enzyme.

So it seems to increase hepatic lipase. So it increases the enzyme
that metabolizes fat for lipolysis and energy production
and reduces something called CIDEC, CIDEC. which is a lipid droplet
associated and lipolysis inhibitor. Now that's a mouthful, no pun intended, but what CIDEC really is
this lipid droplet associated molecule is it can inhibit lipolysis. So extended periods of
time, restricted feeding, meaning eight hour feeding
window or 10 hour feeding window that's obeyed for several months
or more seems to allow the system to shift toward burning
more fat or rather using a higher percentage of fat
when in a caloric deficit. Now I doubt that this is going
to resolve the truly barbed wire, almost hairball, ridiculous online debates
about whether or not time-restricted feeding is
better than another feeding schedule, look, I don't think any particular
feeding schedule is holy. If you are sub caloric, meaning fewer calories burned
than calories ingested, you're going to lose weight. But the data seemed to point
to the fact that if you do time restricted feeding for a
fairly long duration of time, and you maintain that, that you are increasing
these lipases that increase lipolysis energy use from fat, and you're decreasing the lipid
droplet associated lipolysis inhibitors.

So it's both a you're removing
the break and you're pressing on the accelerator of fat loss. I think that this logically
points to a case in which using time restricted feeding with
a sub caloric intake seems to be at least to my mind, the most scientifically
supported way to ensure that a significant portion of the
weight that one loses is from body fat stores. Any discussion about fasting
would be incomplete without a discussion about what does
and does not break a fast.

However, there is no black and white
answer to that question, and you should immediately
understand why it's because eating and not eating are not
equivalent to fed and fasted. It depends on when you ate
how much you ate and where you are in your circadian cycle. We can actually arrive at a
simple answer to whether or not something breaks the fast or not. Now the technical way to go
about this would be to wear a continuous glucose monitor
and to ingest little bits of food, of different kinds
or large amounts of food, of different kinds and
measure blood glucose, because ultimately blood glucose
is the readout of whether or not your system is in
a fed or fasted state. There are other parameters too, of course, but that's the dominant one in so far as the scientific
literature says drinking water will not break your fast
drinking tea will not break your fast drinking coffee, provided it as black coffee
will not break your fast ingesting caffeine in pill
form will not break your fast.

There are other things
that won't break your fast. For instance, eating one peanut when deep in
a fasted state will not break your fast, eating a whole
handful of peanuts might not even break your fast if you are
in a very low glucose state. However, if you just finished a meal
that included carbohydrates, or it was a very large meal
of any kind an hour ago, yes, indeed, eating one peanut
could break your fast. So it's all contextual, that's what's really important to understand, unless you're going to wear
a continuous glucose monitor. And unless you are going to
wear a continuous glucose monitor and set an absolute
numerical threshold for what it is to break your fast. I think there are some simple
rules that we can follow. First of all, anything that
involves sugar in particular, simple sugars can
potentially break your fast.

And there's actually a study on this, which shows that if
people ingest even one, one gram of sugar post dinner, if they had a full meal for
dinner that can actually disrupt the expression of some of the
circadian genes related to fasting and to sleep and
sleep related fasting. Now that's pretty extreme, almost kind of scary to think about, but that's how sensitive our system is. If we already have somewhat
elevated blood glucose from a meal that we ate an hour or so ago, whereas if we have run
for an hour or train hard, high intensity training, and we haven't quite reached
the beginning of our so-called feeding window, will eating
a small amount of food take us out of that fast? Well, depends on what the food is. If it's mostly fat, probably not, a number of
people out there nowadays talk about so-called fat fasting, fat fasting as a way to kind
of regal past the stringency of either eating or not eating
as a black and white rule for feeding window versus non feeding window.

So some people will ingest
medium chain triglycerides so-called MCTs, or people will ingest fats only
until their official feeding window begins. So these are sort of how the
negotiations that people carry out tend to go. But that of course won't increase
blood glucose and insulin as much as carbohydrates will, protein will have sort of
an intermediate effect. And as I mentioned earlier, ingesting carbohydrates with
some fat will tend to blunt the rise in glucose and will
extend the duration over which glucose is released.

So we really can't say food X
or beverage X breaks a fast, however, at the extremes, we
can say that, for instance, if you drink a can of soda pop, unless you just ran an ultra marathon, you're breaking your fast,
okay, eat a piece of pizza, You're breaking your fast,
you eat purely fats, maybe, probably not. If you've been fasting for
five hours or more strictly fasting for five hours or more. So you can start to see where
there's a lot of wiggle room and it's very contextual. And this is why any posts that
you see or any information that you see that something
does or does not break your fast, that doesn't place it in the
context of when the last time you ate and what you ate and
your activity and your time within the circadian clock
schedule of 24 hours, it's a sort of meaningless
discussion, so in general, I think what's really useful
if you're not going to wear a continuous glucose monitor is
to try and be fairly strict about when you initiate your
feeding window and when you stop your feeding window
and as time evolves and you establish a more regular routine
of eating certain kinds of foods and not others that are
right for you because as I've emphasized before on this podcast, and I will continue to emphasize
keto works great for some people, vegetarian keto
works great for some people, carnivore diet works
great for other people.

Some people are omnivores,
some people are carnivores, some people are vegan. All of that is great and fine by me. Everyone has to establish
what's right for them, today, we've really bypass the
discussion about foods of a particular origin or type
animal-based or plant-based. But all the same rules apply
within this thing that we're called intermittent fasting
or time restricted feeding. So what breaks a fast will
depend and what you want to eat or what you are willing to eat. That's a totally separate
manner from when you eat. But as we've established, when
you eat is vitally important, some of you are probably wondering
whether or not artificial sweeteners or non artificial
plant-based sweeteners like Stevia break a fast,
this will vary somewhat.

And I have to say the data
on this are somewhat mixed. There is evidence that when
people ingest artificial sweeteners, that it can create a transient
increase in blood glucose followed by a transient
decrease in blood glucose below baseline. This is thought to explain the
increase in hunger caused by ingestion of things like
aspartame and sucralose and things of that sort.

There are not a lot of
good studies exploring the plant-based non sugar
sweeteners, things like Stevia, even things like monk fruit, which is a separate category unto itself. There aren't a lot of studies on this. I think most people need to
establish this for themselves. The best way of course, would be to wear a continuous
glucose monitor to go into a fasted state of either
one hour or two hours, or maybe you've been fasting
all night and then ingest Stevia in whatever form you
want or coffee in whatever form you want with sucralose
or aspartame, et cetera, setting aside the discussion
about the effects of these things on the gut microbiome, which is a different topic entirely.

I think it's fair to
say that in moderation, the plant-based non sugar
sweeteners like Stevia in particular, Stevia seemed to have a
minimal impact on overall blood glucose when considered over
a fairly large time been aspartame, and sucralose, saccharin. I think we can say more or less the same, but as soon as you get into
a discussion about those, you also have to get into a
discussion about some of the evidence published in nature
and other excellent journals now pointing to the fact
that when consumed in excess, not when consumed in moderation, but when consumed in excess
that those might have some detrimental effects on the gut microbiome.

So do artificial sweeteners break a fast? It depends on the amount
depends on the type. And in general, I think you're probably okay
provided that you're not indulging in them too often, however, some people just by virtue
of tasting something sweet, feel a spike in their appetite
that makes it harder for them to adhere to the feeding window. And so this is why you can
imagine that a really well controlled study on this would
be very hard to carry out. And I'm not really sure that
it's worth our tax dollars to actually design and carry
out a study like that because there would be so much
individual variation in terms of discipline in adhering
to the feeding window, whether or not people experience
increases and drops in blood glucose, how that impacts them, whether or not they're exercising. It just becomes an infinite
variable space, as we say, in experimental science.

So you really have to
determine that for you, but I don't think that we can
fairly say that artificial sweeteners break a fast. I think that would be
incorrect to say earlier, we were talking about
glucose disposal agents, both behavioral and compound
based things like Metformin and berberine, and in fact, cinnamon is even a mild
glucose disposal agent. It can actually reduce blood
glucose, lemon and lime juice, believe it or not, can
lower blood glucose. You may have experienced this
before of eating something very, very sweet and almost feeling
kind of overwhelming on a poisoned by how sweet it is, especially if you're not
accustomed to eating a lot of sugary things. One quick remedy for that is
actually a half lime or half lemon squeezed into juice and
drinking that just by virtue of the taste and by virtue of
the fact that it will reduce blood glucose.

You'll notice that that
effect almost immediately disappears, that's not magic. That's the effects of acidity
on blood glucose levels. So there are a number of
things that can adjust blood glucose, they're not
necessarily disposal agents, they're not sweeping it out
of the bloodstream in the same way that berberine or Metformin would, or that high intensity exercise
at the appropriate times of day would. But there is one particular
thing that one can ingest that can help manage psychologically
and performance wise through the fasting portion of the
intermittent fasting and get you to your feeding window. And that's salt. I've talked a little bit about
this on the podcast before, but because neurons use salt, sodium and potassium and magnesium, the so-called electrolytes in
order to perform their magic of chemical and electrical signaling, everything you do depends on chemical, electrical signaling and all
that chemical and electrical signaling requires electrolytes
in some form or another neurons run on the passage of
ions like sodium in and out of their cell membranes are, I should say, across their cell
membranes to be accurate.

Many people find that the
kind of lightheadedness, the shakiness that's accustomed
with having slightly low blood sugar can be offset by
taking a half teaspoon or so of sea salt, or even just a tiny pinch of
salt and putting into some water and drinking it. Some people find because of
the glucose lowering effects of acidity, that if they're feeling
kind of shaky and not well, and they put some lemon juice
into water and drink that it drops their blood glucose further. So there's a common practice
nowadays that's discussed on the internet of waking up
drinking some water with some lime or lemon juice in it with
a little pinch of salt.

I think that little pinch
of salt is a good idea. What is it doing, how is
it offsetting all this? Well, salt water actually has a mild
effect as a glucose disposal agent, but it has a stabilizing
effect on blood volume. And so, because sodium brings with
it water and the so-called osmolarity of your blood in
your body depends on the salt levels in your blood and brain and body. Many people find that
they're feeling shaky. They're feeling lightheaded.
They can't concentrate. They think they need sugar or food, but what will actually
remedy that is some salt. And I know a number of people
that have incorporated this practice and have written to
me and saying, oh, you know, if I just take a little
bit of salt in some water, they may or may not include
the lemon or lime juice.

They immediately feel better
and find that it's actually quite straightforward to get out to that, to wait until the feeding window kicks in. This is especially true for
people that are using caffeine because when you ingest caffeine, you actually excrete a lot of water, it has a diarrhetic effect. And with that water goes salt. So it actually causes
you to excrete sodium.

Now the role of sodium in
blood pressure and hypertension is, you know, quite
controversial science magazine, one of the premier scientific
journals out there had a special issue all about
salt some years ago, talking about the research
around hypertension, indeed people with chronic
hypertension or high blood pressure or very high blood
pressure in particular should be wary of ingesting too much sodium. But for most people ingesting
sodium provided they drink enough water and they don't
have chronic hypertension or high blood pressure is
actually beneficial. Now that doesn't mean you
should be drinking seawater doesn't mean you should
be overindulging in salt, but many people find that they
can manage their mental and physical state and even
feel really terrific, real clarity of mind, and really enjoy their
fast when they're ingesting sufficient salt.

And all it requires really
is a small pinch of salt, ideally Himalayan or sea salt. If you want to get fancy about it, but table salt would be fine. And just drinking that in some water, maybe with lemon or lime juice
to offset the taste a little bit can really stabilize one's
jitters and can stabilize the mind, and you might also notice
can offset that churning and yearning and appetite where
you can't imagine going another five minutes before eating
something suddenly you feel okay. And that has to do with a lot
of the effects of blood volume caused by ingesting salt
in the appropriate amounts. In other words, sometimes
you think you need food, but what you really need to
salt and salt can make you feel better immediately. I'd like to mention too
excellent zero cost resources. If you're going to explore
time restricted feeding, or maybe if you already are
doing time restricted feeding, I have no affiliation to either of these. The first is the website
that I mentioned before, My Circadian Clock, which is the website hosted by
Satchin Panda and colleagues. There are a lot of resources
there where you can log your food intake, get information about
time-restricted feeding all the science, the ongoing studies, et cetera.

The other is the so-called Zero app. That makes it very easy to
mark when you're beginning your feeding window and when you're
ending your feeding window and in, so doing marking when you are
beginning your fast and ending or fast, where at least initiating the
beginning of the unfed state, as we could more accurately
call it, it's a terrific app. I've used it from time to time. I don't tend to use it in an
ongoing basis because I'm just sort of used to eating at a
particular time of day now. But anytime I've shifted
that window, for instance, a few weeks ago, I started moving that protein
intake in my entire feeding window earlier in the day. And because that takes
some attention on my part, because I'm not used to doing that.

I've been using the Zero app
and I like it quite a lot. It logs your progress and it
gives you averages and you can see how many other
people are fasting again, totally zero cost. I actually
don't know who owns that app, but I think they've done an excellent job. The interface is really
terrific, and as far as I know, it's available for Apple and Android, but it's at least
available for Apple phones, which is the type of
phone I happen to have. So check those out, My Circadian Clock. You just put that into
Google, you'll find it. And the Zero app, both
excellent zero cost resources. In a moment I'd like to review
the parameters of a ideal feeding schedule for you and
give you the variables that you can plug into your lifestyle
and your preferences. There are a couple of things
that I would place into the category of frequently asked somewhat odd, but still worthy of discussion. For instance, people have asked will brushing
your teeth with toothpaste, break your fast? I think unless you're
swallowing the toothpaste, no.

Now if you really want to
run out and get a continuous glucose monitor and brush your teeth, and you can evaluate that, but no people have asked will
a half glass of wine after dinner a couple hours after
dinner break your fast. Absolutely. It absolutely will. And it's been demonstrated to
do that based on the one gram of sugar, kind of eerie or scary effect
that I talked about before, scary and eerie, because it just seems
like one gram of sugar. How could it do that? But these are metabolic
processes and they are very sensitive, post-meal, a few months back, I did an experiment wearing
a continuous glucose monitor. And I got a surprise when I
discovered that going into a sauna increases my blood
glucose quite a bit. It actually spikes it as high as a meal. And then it tends to drop
back down to baseline or even slightly below baseline afterwards, when I talk to people about
this, somebody said, oh, it's got to be that the
continuous glucose monitor was getting disrupted by
the heat in the sauna.

That's actually not the case. Turns out that when you go in a sauna, because you dehydrate,
you're losing water, I wasn't drinking water and
you're dropping a lot of water. The concentration of sugar in
your blood actually goes up. And I actually put these data
out in a social media post on Twitter, and people were kind of shocked
to see how much a sauna can spike your blood glucose,
now I do practice time, restricted feeding, intermittent fasting. I'm not super strict about it.

I use a kind of eight to 10
hour ish window either early in the day or late in the day. I saw this effect of
the sauna, personally, the psychological and physical
health effects of the sauna are valuable enough to me
that I continue to use it. I'm just not concerned about
this increase in blood glucose, to the extent that I'm
going to eliminate sauna. I like to use the sauna three
or four times a week before sleep, so I'll use it an
hour or two before sleep. And yes, indeed it creates this big
spike in blood glucose that then drops based on change in the
concentration of blood sugar.

I'm just not going to worry about it, now, if you're concerned about
blood glucose spikes, then you might be worried
about it, but in my case, it was one of those things
where it was interesting and it was worthy of discussion. I thought because it was
somewhat surprising to me, although it makes perfect sense
why this would be the case, but at the end of the day, literally, it just makes sense for
me to get in the sauna. Okay. So now you've
heard a lot of science.

You've heard a lot of
examples, even a few anecdotes, and let's come up with the
ideal intermittent fasting, AKA time, restricted
feeding schedule for you. And when I say ideal, I mean, what are the variables
that are negotiable? What are the ones that are non-negotiable? What is ideal for you will
depend on the context of your life and what you are
willing to do consistently. So, first of all, we established based on the
discussion with Satchin, who is truly the premier
world expert in this area, who knows the animal and human
scientific literature better than anybody has written
this incredible review. And for whom I consulted that you do not want to ingest
food for at least I want to emphasize at least 60 minutes
post waking up, second, you want to avoid ingesting
any food of any kind, even one gram of sugar, remember, this is the ideal one gram of
sugar even would be too much for the two to three
hours prior to bedtime.

He also mentioned, ideally, you are spending eight hours in bed. I didn't tell you that
earlier. I saved that for now, but ideally you are sleeping
that entire eight hours, but simply by being in bed for
that eight hours and avoiding food after waking for an hour
and before bed for two to three hours, you're starting to build out
the duration of this fasted period. Remember that the sleep
related fasting is particularly important for the health
benefits of time-restricted feeding. Again, the sleep-related fasting is
especially important because of all the cellar repair processes
that occur in the liver and the gut in the microbiome, in
the brain all over the body. And because of the way that
that coordinates the expression of the clock genes that are
then going to wick out and have many other positive effects on health, including weight and fat loss. But in addition to that
liver health, et cetera, an eight hour feeding window
as a target seems to be the best target feeding, at least
by my read of the literature. And in discussing it with
shuts such in shorter feeding windows of four to six hours, tend to lead to overeating
and potentially increases in weight.

One meal per day type eating
do not seem to do that, but those are special cases in
that most people can't adhere to a one meal per day type schedule, at least not on a regular basis. And it's not very compatible
with most social schedules. Although some people may be
able to adhere to that in a straightforward way, but there aren't any robust
studies exploring the advantages of one meal per day. So if you feel there are
advantages of one meal per day for you as opposed to an
eight hour feeding window, well then by all means, use a one meal per day approach
or use a four to six hour feeding window and just make
sure you don't overeat in that window.

Remember that most people tend
to not adhere to the eight hour feeding window, they say eight hours, but they tend to eat outside
of the eight hours a little bit on each side, so if your goal
is a 10 hour feeding window, you might want to set it to
nine hours or eight hours. If your goal is six hours, you might want to set it
to seven or eight hours. And this is simply based by, I shouldn't say simply
this is based on thousands, if not tens of thousands of
human subject data points that Satchin and colleagues have collected regular placement of the eating
window or feeding window, every 24 hours is important.

You don't have to be absolutely
rigid and neurotic about this, but you don't want it sliding
around on the weekends so that it starting two hours later
and ending two hours later, a couple days a week, because then you start to offset
many of the positive health effects that have been
demonstrated for time restricted feeding. Remember if you eat your
food within a certain feeding window, but that feeding window
shifts by a couple of hours, it is effectively like
jet lagging your system. It is effectively like traveling
a couple times zones over eating there for a few days
and coming back when in fact you're not traveling, that's because of the
way that food adjusts, the circadian clock genes. Now you can offset some of
that through the use of light. And I've talked extensively
about how to use light in previous podcasts, but again, early morning and all day bright, light exposure as safely as
you can, ideally from sunlight, not through a window, et cetera, avoiding bright light in
the middle of the night, extremely important for mood offsetting, metabolic dysfunction, et cetera, not incidentally Satchin's early work was, he was one of the three
co-discoverers of the cells in the eye, the so-called melanopsin
cells that set the central circadian clock.

So he was
a pioneer in that field, which led him to be a pioneer
in this field and so on. When should that eight hour
window be placed within each 24 hour cycle? Well, let's
talk about ideal ideal. If you really want to maximize
all the health benefits of time-restricted feeding, you need to extend the fast
around sleep on both sides. You would place it smack dab
in the middle of the day.

It would be a schedule in
which you started eating for instance at 10:00 AM. And you
stopped eating at 6:00 PM. An absolutely dreadful schedule
for anyone that wants to have some semblance of a
normal life. In my opinion, it's not really compatible
with most schedules. Although some people
might be able to do it, maybe you and your family or
your friends, your, you know, you're eating a late breakfast or a, and then you're having a
late-ish lunch around 2:00 PM. And then you have dinner at six. And then assuming that you
go to bed around nine 30 or 10:00 PM, that is going to extract
the maximum amount of weight related body fat related metabolic
factor related aspects of time, restricted feeding.

Some people tend to fall into
a category where they do best placing that feeding window
later in the day and provided it. Doesn't run too close to your sleep. Remember you needed a two or
three hour buffer before your sleep, where you're not ingesting
anything that's in order to extract the benefits of
time-restricted feeding. Well then starting your
feeding window at 12:00 PM and ending at 8:00 PM plus or
minus half an hour or so day to day, it seems like a perfectly
reasonable schedule for some people starting at 2:00 PM
and ending at 10:00 PM will be that schedule. Of course, you have to take into
consideration when you exercise. If you exercise. For instance, I like to exercise
early in the day if I run, or if I do some moderate or
light intensity exercise, regardless of what type of exercise it is, I have no trouble waiting until
my feeding window kicks in around noon or even 2:00 PM. But if I do high intensity
weight training, for instance, early in the day, or if I run sprints and I do
that at 7:00 AM or 8:00 AM by 11:00 AM, I am very, very hungry and it's hard
for me to do other things concentrate, et cetera.

Now I'm not neurotic
about my feeding window. As I mentioned before, I kind of let it expand and
contract a bit around the eight hour mark, and feel perfectly
free to do that too. We're talking here in, in ideals, not in necessarily practicals, but other people find that
they're very hungry when they wake up early in the day. If you're one of these people
or you're somebody who really is trying to emphasize hypertrophy
or maintenance of muscle, then it does seem that ingesting
protein early in the day is beneficial.

That it can be more readily
converted into muscle tissue. And this has been demonstrated
in at least one study. There's another study underway. That's exploring this further
for people that are really, really interested in hypertrophy
and building muscle will then time-restricted feeding
is usually not the way they go. I mean, let's be honest. There are many people out
there who are eating four more meals per day, and they're doing that
from 7:00 AM until 8:00 PM.

I realized that not
everybody is overweight. There is an obesity crisis. Indeed. You know, the percentage of obesity
and non-alcoholic fatty liver disease is just cosmic through the roof, at least in this country and
in other countries as well, this country meaning the US
but other countries as well. But there are of course, people that are trying to gain
weight through who don't want to lose weight or who are
trying to maximize physical performance or hypertrophy
or things of that sort. And so of course time-restricted
feeding for them might be as long as I'm awake, I'm eating. And I, you know, I tip my hat
to those people and just say, you know, provided you understand what
you're doing and the burden that, that places on some of the
other processes in your body, if that's right for you, then
by all means pursue that.

Another thing that we can add
to this summary or key points related to time restricted
feeding is the use of glucose, disposal, agents, and or behaviors. If you find that you've eaten
too close to a period of time in which you would prefer to be fasting, that's when a 30 minute brisk
walk or even modest walk after eating can be beneficial, ingesting some lemon juice
or lime juice can help lower blood glucose somewhat. And then there are the things
like Metformin and berberine there, even some supplements out
there that combine things like berberine cinnamon, which can lower blood glucose
and things like chromium and things that have a mild
effect on blood glucose, but berberine and Metformin
are very high potency glucose disposal agents.

And I mentioned earlier why you
would want to approach those with the appropriate level
of caution and figure out the dosages for you, and, and for some people, the dosages will be zero
milligrams is going to be ideal. And then of course we discussed
how making sure that you're ingesting enough fluids in
particular water and salt, especially if you're using
caffeine in order to increase your levels of alertness, regardless of where that caffeine
source comes from coffee, tea, or otherwise, that can cause the excretion
of sodium and can lead to a kind of shakiness, a lightheadedness and the
feelings of hunger that may or may not be related to blood glucose.

Some people genuinely need to eat. I certainly would not
want to see people getting hypoglycemic to the point
where it's dangerous. Certainly if you are
diabetic, you, and in fact, for all people, you should consult with your
physician when exploring any major changes to diet or
additions or subtractions of anything, including supplementation, but for most people maintaining
relatively low to modest blood glucose levels is going
to be pretty healthy and will allow all the positive effects
of intermittent fasting to occur.

And when you find that reaching
that start to the feeding window is challenging that
ingesting sodium can often stabilize your system
mentally and physically, and allow you to reach that
window often painlessly. And then as a final point,
as I mentioned earlier, provided that they are consumed in low, no or modest amounts,
artificial sweeteners, or plant-based non sugar, non caloric sweeteners don't
seem to really impact blood glucose to the extent that
it would quote unquote, take you out of your fast, but that like fat fasting is
something that's going to be highly individual, and that you're going to
have to experiment with for yourself and being able to
recognize when you're in a fast and when you're out of a fast, at a subjective level and not
constantly having to measure your blood glucose or do
things of that sort can be beneficial.

And I think if you watch for
the feelings associated with eating and post eating foods
of different kinds in different amounts, and you watch for the feelings
associated with being fasted for long periods of time or
short periods of time of having gotten sufficient sunlight
of having trained harder, not trained hard earlier
that day, et cetera, you can do the most important thing, which is to start to learn,
to evaluate your own system, to run simple, safe experiments on your system
in a way that allows you to really establish the ideal
nutrition schedule for you, whether it be time restricted, feeding, AKA intermittent fasting, or
some other nutritional plan. If you're learning from and
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of information today. I hope you learned a lot about
time, restricted feeding. I hope you learned a lot about
metabolism and energy and health and how when you eat is
as important as what you eat, and last, but certainly not least thank
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