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Effects of Fasting & Time Restricted Eating on Fat Loss & Health | Huberman Lab Essentials — Transcript

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0:00Welcome to Huberman Lab Essentials,
0:02where we revisit past episodes for the
0:04most potent and actionable science-based
0:06tools for mental health, physical
0:08health, and performance.
0:11I'm Andrew Huberman, and I'm a professor
0:13of neurobiology and opthalmology at
0:15Stanford School of Medicine. What we're
0:17going to talk about today is how
0:19intermittent fasting aka timerestricted
0:22feeding impacts weight loss, fat loss in
0:25particular, muscle maintenance and loss
0:27and gain, organ health such as gut
0:30health and liver health, the genome, the
0:33epiggenome,
0:35inflammation, sickness, recovery and
0:38healing from sickness, exercise,
0:40cognition, mood, and lifespan. So, let's
0:44talk about eating and what happens when
0:45you eat. and let's talk about fasting or
0:48not eating and what happens when you
0:50fast. If ever there was a topic that is
0:53controversial, especially on the
0:54internet, it is that of diet and
0:56nutrition. So, I'm waiting into this
1:00with a smile and in eager anticipation
1:02of all the but but but this and but but
1:05that and wait but this showed that.
1:08Here's the deal. We need to precisely
1:10define what it is that we're talking
1:12about when we talk about nutrition.
1:15I'm going to give you an example of a
1:16study that was published a few years
1:18ago, 2018, by a colleague of mine at
1:21Stanford. Chris Gardner is a terrific
1:25professor of nutrition and has done a
1:28lot of important studies on how
1:30nutrition impacts different aspects of
1:32health. This paper where Chris is the
1:36first author, it's gardener at all 2018
1:38jamama
1:40looked at weight loss in people
1:44following one particular diet versus
1:46another particular diet. And this was a
1:4812-month weight loss study. So it was
1:50focused specifically on weight loss,
1:52although they looked at some other
1:54parameters as well. And the basic
1:56conclusion of the study was that there
1:58was no significant difference in weight
2:00change between people following a
2:02healthy low-fat diet versus a healthy
2:05low carbohydrate diet with significantly
2:07more dietary fats in them.
2:10This caused a lot of ripples in the
2:13world of nutrition and nutritional
2:15science and certainly in the general
2:17population because anyone that
2:19understands diet and nutrition would
2:22immediately say, "But wait, there are
2:24all sorts of different implications of
2:26eating one type of diet, say low
2:28carbohydrate, higher fats versus a
2:30higher carbohydrate, lower fat diet."
2:32And indeed there are. This study was
2:35focused specifically on fat loss and on
2:38weight loss. So as we discuss
2:42timerestricted feeding we need to be
2:44very precise about what are the effects
2:46of timerestricted feeding and of eating
2:49in particular ways at particular times.
2:52We are going to emphasize again whether
2:54or not the study was done in mice or in
2:56humans in athletes in men and women or
2:58both. But the study from Gardener and
3:00colleagues is a beautiful study and
3:03really emphasizes that if one's main
3:06goal is simply to lose weight, then it
3:09really does not matter what one eats,
3:12provided that the number of calories
3:14burned is higher than the number of
3:17calories ingested. However,
3:20anyone out there who understands a
3:23little bit of biology or a lot of
3:25biology will agree that there are many
3:28factors that impact that calories burned
3:30part of the equation. Some of those are
3:32obvious. So, for instance, amount of
3:35exercise, type of exercise, basil
3:38metabolic rate, how much energy one
3:40burns just sitting there. I've talked
3:41before on this podcast about NEAT,
3:43non-ex exercise induced thermogenesis,
3:45where if people bounce around a lot and
3:47fidget a lot, they can burn anywhere
3:49from 800 to 2,000 calories per day. So,
3:52their quote unquote basil metabolic rate
3:54is actually much higher simply because
3:55they're fidgeters, whereas people who
3:57tend to be more stationary have a lower
3:58basil metabolic rate on average. There's
4:01great science to support this. Metabolic
4:04factors and hormones are also very
4:07important. hormones such as thyroid
4:09hormone and insulin and growth hormone
4:12and the sex storage hormones
4:13testosterone and estrogen those levels
4:15will also profoundly influence the
4:18calories out the calories burned
4:20component of the calories in calories
4:22out equation. So if out there on the
4:25internet or in listening to a particular
4:28podcast or speaker somebody says this is
4:30the ideal diet or calories in calories
4:33out does not matter or calories in
4:35calories out is the only thing that
4:36matters. I think it's very important to
4:38understand that there are some
4:39foundational truths such as calories in
4:41calories out but that of course hormone
4:45factors and the context in which a given
4:48diet regimen is taking place are
4:50exceedingly important. So there's no way
4:54that we can drill into every aspect of a
4:56given feeding plan or feeding schedule
5:01that would allow us to tap into every
5:03aspect of the list that I read out
5:05before. Weight loss, fat loss, muscle,
5:07organ, genome, epigenome, inflammation,
5:08exercise, cognition, mood, and lifespan.
5:11But today we're going to be very precise
5:12about how timerestricted feeding, it's
5:16very clear from both animal studies and
5:18human studies can have a very powerful
5:21and positive impact on everything from
5:24weight loss and fat loss to various
5:27health parameters. This is a beautiful
5:30literature that's emerged mostly in the
5:32last 10 or 15 years. So there is a
5:35perfect diet for you and today I'm going
5:37to arm you with the mechanisms and
5:39understanding that will allow you to
5:41define what that perfect diet is and
5:43will allow you to eat on a schedule and
5:46will and to eat the things that are
5:48going to best serve your goals. Some
5:50simple rules about eating. First of all,
5:52when you eat, typically your blood
5:55glucose, your blood sugar will go up.
5:58Also, insulin levels will go up. Insulin
6:01is a hormone that's involved in
6:03mobilizing glucose from the bloodstream.
6:06How much your glucose and insulin go up
6:09depends on what you eat and how much you
6:11eat. In general, simple sugars,
6:15including fructose from fruit, but also
6:17sucrose and glucose. And simple sugars
6:20will raise your insulin and blood
6:22glucose more than complex carbohydrates,
6:25things like grains and breads and pastas
6:27and so forth. and grains and breads and
6:30pastas and so forth will raise your
6:31blood glucose more than fibrous
6:33carbohydrates like lettuce and broccoli
6:35and things of that sort. Protein has a
6:39somewhat moderate or modest impact and
6:41fat has the lowest impact on raising
6:44your blood glucose and blood insulin. So
6:48what you eat will impact how steep a
6:50rise in blood glucose and insulin takes
6:53place. And there are a number of factors
6:55that are related to your individual
6:57health that will also dictate how steep
6:59and how high that rise in glucose and
7:01insulin will be. The longer it's been
7:04since your last meal, the lower
7:06typically your blood glucose and insulin
7:08will be. and the higher things like
7:11GLP-1 glucagon
7:13like peptide one glucagon being a
7:17hormone that's also secreted when you
7:20are in a fasted state or a low blood
7:23glucose state. It's involved in
7:26mobilizing various energy sources from
7:28the body including fat through what we
7:30call lipolysis
7:32also using carbohydrates and potentially
7:34even using muscle as a source of energy.
7:36So that's kind of a fire hose of
7:41information about what happens when you
7:42eat and don't eat. But just think of it
7:44this way. Blood sugar and insulin go up
7:46when you eat. They go down when you
7:48don't eat. And other hormones go up when
7:51you don't eat. So there are hormones
7:52associated with the fasted state and
7:55there are hormones associated with the
7:56eating and having just eaten state.
8:00Now the most important thing to
8:03understand is that like everything in
8:06biology this is a process that takes
8:09time. So insulin and glucose go up when
8:12we eat and it takes some period of time
8:14for them to go down. Even if we stop
8:16eating they will remain up for some
8:19period of time and then go back down. It
8:21takes time. This is very important
8:24because if you look at the scientific
8:26literature on fasting on timerestricted
8:29feeding
8:31it's absolutely clear that the health
8:33benefits not just the weight loss
8:35benefits but that the health benefits
8:37from timerestricted feeding occur
8:39because certain conditions are met in
8:42the brain and body for a certain amount
8:45of time. And that gives us an anchor for
8:48from which to view what eating is in
8:51terms of how it sets conditions in the
8:53body over time. And if that sounds
8:56overly analytic, I promise you this is
8:59the simplest and best way to think about
9:01any eating schedule or any eating plan.
9:04So I think it's fair to say that in the
9:06field of nutrition there are a few
9:08landmark studies that serve as really
9:11strong anchors for building our
9:13understanding of what to eat and what
9:15not to eat and when to eat depending on
9:17our goals. The Garner study that I
9:19mentioned earlier is one such study in
9:22that it says if your goal is weight
9:24loss, it really does not matter what
9:28foods you consume provided that you
9:30consume a submaintenance caloric diet.
9:33However, I want to emphasize again that
9:37sets aside issues of adherence, meaning
9:40how easy or hard it is to adhere to a
9:42given diet. Some people find it much
9:44easier to follow a highfat, low
9:46carbohydrate diet. Some people follow
9:48follow a different diet because it's
9:49much easier for them to follow. And some
9:52people are concerned with mental
9:53performance and athletic performance.
9:54So, that study doesn't say there's a
9:57best diet. What it says is that what you
9:59consume is less important than the
10:02amount of food that you consume, at
10:04least for sake of weight loss, not
10:07necessarily for sake of health. Now, the
10:10study that I'm going to refer to next is
10:13what I would consider the second major
10:15pillar of nutritional studies. This was
10:17a paper in mice that set the basis for
10:20studies in humans that came later. And
10:22the title of this paper is
10:24timerestricted feeding without reducing
10:26caloric intake prevents metabolic
10:28diseases in mice fed a highfat diet. So
10:32the title tells us a lot. It says that
10:34what's varied in this study is not what
10:37these mice ate. It was when they ate it.
10:41One of the most important things to take
10:42away from this study was that mice that
10:44ate a highly palatable high-fat diet, a
10:47great tasting diet, but only during a
10:49restricted feeding window of each
10:5124-hour cycle maintained or lost weight
10:54over time. Whereas mice that ingested
10:58the same diet, same amount of calories,
11:01but had access to those calories around
11:03the clock gained weight, became obese,
11:06and quite sick. And as an additional
11:09second point, the mice that restricted
11:12their feeding window to a particular
11:14portion of eight hours of every 24-hour
11:17cycle actually showed some improvement
11:21in important health markers. And what
11:24was even more incredible is that mice
11:26that only ate during a particular
11:28feeding window also experienced some
11:31reversal of some prior negative health
11:34effects. Not only did restricting food
11:37to a particular phase of the 24-hour
11:39cycle benefit things like lean body mass
11:43and fat loss and a number of health
11:46parameters that I'll talk about in a
11:47moment. But it also anchored all the
11:50gene systems of the body and provided a
11:53more regular stable so-called circadian
11:55rhythm or 24-hour rhythm. You may be
11:57surprised to learn that 80% 80% of the
12:01genes in your body and brain are on a
12:0624-hour schedule. That is, they change
12:08their levels going from high to low and
12:11back to high again across the 24-hour
12:13cycle. And when those genes are high at
12:16the appropriate times and low at the
12:17appropriate times, meaning their
12:18expression is high and low at the
12:20appropriate times and therefore the
12:23proper RNAs and proteins are made
12:25because DNA and codes for RNA, RNA is
12:27translated into proteins.
12:30When that happens, your health benefits
12:34when those genes are not expressed at
12:36the right times. When they're high or
12:38low at the wrong times of each 24-hour
12:40cycle, that's when you get negative
12:42health effects. And while this was in
12:44mice, we now know that this also occurs
12:46in humans. So if you want to be healthy,
12:49you want your organ health, your
12:50metabolic health to be entrained
12:53properly, one of the most important
12:55things you can do is to eat at the
12:57appropriate time of each 24-hour day.
12:59When mice can eat around the clock, bad
13:02things happen. And one of the bad things
13:03that happens is that the liver suffers.
13:06fatty deposits in the liver, other
13:09factors in the liver, essentially taking
13:11down the pathway of liver disease. The
13:13timerestricted feeding essentially
13:16reversed that or led in many cases to
13:19even healthier liver condition. So,
13:21restricting your feeding to a particular
13:22window every 24-hour cycle has clearly
13:25been shown now in mice and in humans to
13:28enhance liver health, which is
13:30wonderful.
13:31How does it do this? Well, it happens
13:34because food intake, as I mentioned
13:37earlier, sets certain conditions in the
13:39body that last for a period of time.
13:41Anytime we eat, there's a period of time
13:44that's required for so-called digestion,
13:46but also gastric emptying and other
13:49processes related to breaking down that
13:51food and utilizing it. That process of
13:53breaking down food involves certain
13:56cellular functions that if they're
13:58ongoing throughout the 24-hour cycle or
14:02even extended too far across the 24-hour
14:05cycle, meaning you're eating across a 14
14:07or a 16 hour or an 18 hour window, that
14:10causes serious problems. So, by eating
14:12around the clock, you're making yourself
14:14sicker. By eating at restricted periods
14:17of time each 24-hour day, you're
14:19actually making yourself healthier and
14:21you're activating certain processes that
14:24can positively impact both weight,
14:27either maintenance or loss of weight,
14:29and blood glucose regulation. As we move
14:33forward and we talk about intermittent
14:34fasting, I want to start to establish a
14:37foundational protocol that all of us,
14:40any of us can use in order to maximize
14:43your particular goals. There are some
14:46absolutes within this realm of
14:48timerestricted feeding. Here are a
14:51couple of absolutes that you would want
14:52to consider. First of all,
14:55it pays off in the metabolic sense and
14:59in the health sense and in the weight
15:01maintenance or loss sense to not ingest
15:05any food in the first hour after waking
15:08and potentially for longer. The second
15:11major pillar that's well supported by
15:13research is that for the two and ideally
15:17three hours prior to bedtime, you also
15:20don't ingest any food or liquid calories
15:23for that matter. So let's deal with this
15:25first question of when is the ideal
15:27feeding window. And here again, we're
15:29thinking about a schedule of eating that
15:32involves eating at least once every 24
15:34hours, not two day or three day or every
15:37other day fast. So it turns out that the
15:39answer to the question when is it best
15:41to eat is actually best answered by
15:44thinking about the other side of the
15:46coin which is when is it best to fast.
15:49So because we are fasting during sleep
15:52it's very clear that it's best to extend
15:55the sleepreated fast
15:58either into the morning or to start it
16:01in the evening. Now this might seem kind
16:04of obvious but it's actually not so
16:06obvious. You could place that feeding
16:08window early in the day, middle of the
16:11day, or late in the day. Let's think
16:13about what happens when we sleep. When
16:15we sleep, our body undergoes a number of
16:18different processes in the brain and
16:20body in order to recover the cells and
16:22tissues. Many of you have probably heard
16:24of autoagi, which is essentially a
16:26cleaning up, a gobbling up of dead cells
16:29and cells that are injured or sick. And
16:31this is a natural process that occurs
16:33and it occurs mainly during sleep
16:35although not only during sleep.
16:39Fasting of any kind does tend to enhance
16:42autoagi. So when we're asleep the bad
16:45cells are getting gobbled up and eaten
16:47and the good cells also are undergoing
16:50certain repair mechanisms mainly related
16:52to or at least governed by those
16:54circadian genes that we talked about
16:56earlier, those clock genes. So, one
16:58thing is certain that you want your
17:00eating window to be tacked or attached
17:04to your sleepbased fasting in a way that
17:08makes it easier for you to get into the
17:10fasted state for a period of time. Now,
17:13most people find it very hard to only
17:15eat in the middle of the day. So while
17:17that's best, it's ideal for sake of the
17:20fasting related improvements in health,
17:22it is not ideal and it's not very
17:26applicable to most work and family and
17:28social situations.
17:30Most people eat breakfast with others
17:32andor eat dinner with others. But in
17:34general, it's hard to restrict your
17:36feeding window to just the absolute
17:38middle of the day. But from a purely
17:40health perspective, in a very objective
17:42way, that would be the ideal situation.
17:45it does appear beneficial to grab a hold
17:49of that sleepreated fast, meaning you
17:53don't want your feeding window to be too
17:56close to bedtime. And that's why we came
17:57up with this kind of foundational
17:59pillar, which is at least no eating for
18:02the first hour after waking, but also no
18:04eating within 2 to 3 hours prior to bed.
18:07So from both a practical and a health
18:10perspective and a purely objective view
18:13of how intermittent fasting works and
18:16can benefit us, starting to eat each day
18:20somewhere around 10:00 a.m. or around
18:23noon and then allowing a feeding window
18:26that goes until 6 or maybe 8:00 p.m.
18:31That seems to me like the kind of
18:32schedule that will allow you to get the
18:35most out of intermittent fasting,
18:36timerestricted feeding,
18:39but does not set you up to be really out
18:41of sync with the social rhythms in most
18:43cultures.
18:45If you think about it from the
18:46perspective of say a noon to 8 feeding
18:50window, what you'll find is that you're
18:52able to eat lunch with others if you
18:55like or by yourself. You will be able to
18:57eat dinner at a reasonable hour. At
18:59least in most countries, in most
19:00cultures, eating dinner somewhere
19:02between 6:30 and 7 p.m. is typical.
19:08When you say a feeding window that goes
19:09until 8, that doesn't mean sitting down
19:11to dinner at 8. That means your last
19:13bite of food or ingestion of any liquid
19:15calories was at 8:00 pm.
19:18Assuming that you go to bed somewhere
19:20between 10 p.m. and 1:00 a.m., that
19:22allows this tapering off or this
19:24transition from feeding to a fasted
19:27state and still allows you to capitalize
19:29on the special period of fasting that is
19:32sleepreated fasting. And again, I want
19:34to emphasize that the fasting that
19:36occurs during sleep is vital and eating
19:38too close to sleep will disrupt that
19:40fasting related sleep. The important
19:42thing here is to establish a feeding
19:44window that you can comfortably manage.
19:47Okay? Meaning that on average you can
19:50obey an 8 hour feeding window or a
19:5210-hour feeding window and then to place
19:54that feeding window in a social and life
19:57context that you can manage on a regular
20:00basis. Now, there are two key points
20:02that have been gleaned from the
20:04scientific data about this feeding
20:05window and when to place it. First of
20:08all, we can say is that the 7 to N-hour
20:11feeding window produces all of the major
20:14health benefits of timerestricted
20:16feeding as well as being pretty
20:19straightforward for most people to
20:20adhere to on a regular basis and on a
20:23regular basis turns out to be very
20:24important. I'll get back to that point
20:25in a moment. Whereas the 4 to 6 hour
20:27eating window doesn't seem to serve
20:29people as well as say a seven or eight
20:31hour eating window simply because people
20:33are overeating during that eating
20:35window. So, let's talk about some
20:36conditions where having the feeding
20:38window early in the day would actually
20:40be very beneficial. If your main
20:43interest is maintaining and/or building
20:45muscle,
20:46then it can be beneficial to ingest
20:48protein early in the day. You would
20:50still want to obey this what we're
20:53calling a kind of foundational rule of
20:56no not eating any food for the first
20:58hour post waking. And the cut off for
21:01when you would want to eat protein would
21:03be sometime before 10:00 a.m. And there
21:06I'm averaging across a number of
21:07different situations. Now, it's not as
21:11if at 10:01 a.m. a gate slams shut and
21:14you can't generate hypertrophy. Of
21:16course, that's not the case. However,
21:18it's very interesting that it doesn't
21:20matter when the resistance training, the
21:22loadbearing exercise occurs in the
21:2424-hour cycle. So whether or not, in
21:27other words, people are training early
21:29in the day or they're training late in
21:30the day,
21:32it still appears that ingesting protein
21:34early in the day favors hypertrophy. So
21:38obviously we don't want to be overly
21:39neurotic about this stuff, but because
21:40this is an episode about the science of
21:42intermittent fasting and timerestricted
21:44feeding, as important as how long your
21:48feeding window is is where that feeding
21:51window resides in each 24-hour cycle.
21:54And perhaps even more important than
21:56that is that it be fairly regular where
21:59that feeding window resides. Because
22:01even if you have a very short feeding
22:02window, if it's drifting around from day
22:04to day, that actually offsets a number
22:07of the positive health effects of
22:09intermittent fasting. Along those lines,
22:11however, there are things that we can
22:14all do that will allow us to offset some
22:17of the drift, if you will, that we
22:21experience or that we induce in terms of
22:23when our feeding window occurs or that
22:25the feeding window might push out a
22:27little later and then therefore start a
22:29little later the next day. There are
22:31things that we can do and there are
22:32things that we can take. And so, I'd
22:33like to discuss those briefly. So
22:35throughout this episode, I've more or
22:37less been alluding to the fact that when
22:40you eat, there's some period of time
22:42afterwards in which you're actually
22:44still eating, at least from the
22:45perspective of metabolism, because
22:47glucose is up, insulin is up, and you're
22:50undergoing different metabolic and
22:52digestive processes that don't really
22:55speak to you being in a fasted state,
22:58right? It's not just about when you take
23:00your last bite or your last sip.
23:02However, there are things that we can do
23:05to accelerate the transition from a fed
23:08state to a fasted state. And so, I'd
23:13like to discuss what those are. So,
23:14there's a fun and exciting concept which
23:16is glucose clearing.
23:18You may have heard the old adage that if
23:20you take a 20 or 30 minute walk after
23:23dinner that it accelerates the rate at
23:26which you digest that food. And indeed
23:27it does. So, for instance, if you were
23:30to eat a meal that ended at 8:00 p.m.
23:34and then plop to the couch, it would be
23:375 or 6 hours until you have transition
23:39from a fed state to a fasted state.
23:42However, you can accelerate that
23:44considerably by taking a 20 or 30 minute
23:47just light walk. And this gets back to
23:50this key feature of our biology which is
23:52that what we eat when we eat when we
23:55exercise when we view light. It's about
23:57setting a context or a set of conditions
24:00in your brain and body. So it's not so
24:02much about the activities that you
24:03undergo. It's about the activities you
24:06undergo and their relationship to one
24:08another over time. And so in this way it
24:12really beautifully highlights the way
24:13that your biology is interacting all the
24:15time. Now, there are other ways to clear
24:17out blood glucose
24:19that involve supplements or prescription
24:22drugs. These are so-called glucose
24:24disposal agents. Glucose disposal agents
24:28such as metformin, which is a
24:30prescription drug, or bourberine, which
24:32is an over-the-counter substance, will
24:35lead to very dramatic reductions in
24:37blood glucose. Now, I've tried
24:39bourberine before, and what I can tell
24:40you is that if you take bourberine,
24:43which by the way is very much like
24:44metformin, its effects are almost
24:46identical to metformin, in fact, but
24:47it's much less expensive and it's
24:49over-the-counter. If you take bourberine
24:51and you have not ingested carbohydrates,
24:54many people, including myself,
24:56experience a splitting headache. You
24:58become hypoglycemic because it is a
25:00glucose clearing agent. Nowadays, there
25:03are a number of commercially available
25:05continuous glucose monitors. I've tried
25:07one of these. It involves putting uh
25:09what's essentially a patch with a little
25:11needle that goes into your skin which is
25:12continuing continually, excuse me,
25:14monitoring your blood glucose and you
25:16can look at it at an app on your phone
25:17and you can learn a lot that way about
25:19how different foods impact the increases
25:22and decrease in blood glucose. If you're
25:24doing experiments with bourberine or
25:25metformin, you can see how those impact
25:28your blood glucose. You can see how
25:30exercise, hit training, or otherwise
25:31impact impacts blood glucose. Excuse me.
25:34Again, I have to say that glucose
25:37clearing agents that involve a walk or
25:40exercise, moderate or intense, are going
25:42to be a lot easier to titrate and adjust
25:46the levels of than things that you're
25:47going to take where you have to ingest
25:49the dosage. And then once you ingest a
25:50certain dosage, you're along for the
25:52ride, at least until the effects of that
25:54particular compound wear off. In the
25:56fasted state, a number of different
25:59proteins that are expressed in cells
26:01undergo changes in their expression.
26:03When we are fasted, we tend to reduce
26:06the activity of a particular protein
26:08called mTor, mamalian target of
26:10rapamyosin. mTor is very active in cells
26:14while they are growing. So one way I'd
26:16like you to think about the fed state is
26:18that when you eat or when you don't eat,
26:20when you're fed, when you're fasted, you
26:22are either promoting cellular growth of
26:24all kinds or you're promoting cellular
26:27repair and clearance of all kinds. And
26:29so again, this is about setting
26:31conditions in the brain and body. It's
26:33not so much about when you eat food A or
26:36B, it leads to increases in mTor.
26:40Anytime you eat any food, doesn't matter
26:42if it's plant-based, animal-based, fat,
26:45protein, carbohydrate, doesn't matter.
26:47You are biasing your system towards a
26:48biochemical state of cell growth. And
26:51anytime you haven't eaten for a while or
26:53blood glucose is low, you are biasing
26:56your system toward a state of cellular
26:58repair. And this is why people who do
27:01not suffer from any blood glucose
27:04regulation issues take things like
27:06bourberine as glucose disposal agents or
27:08take metformin. I'm not necessarily
27:10suggesting that you do that, but it's
27:12because those things mimic fasting. They
27:14create situations in the body that
27:16promote things like AMPK and the
27:18certuins and others to push your body
27:20and your system down a route of repair
27:23even though you might have just eaten a
27:24meal an hour ago. Along the lines of the
27:26health benefits of intermittent fasting,
27:29there are nice data showing improvements
27:31in the gut microbiome
27:34and in particular in the treatment of
27:37irritable bowel syndrome and other forms
27:39of colitis. It appears that intermittent
27:42fasting can reduce the amount of
27:46so-called lactobacillus that's present
27:48in the gut. And lactose bacillus is when
27:51in high levels is correlated with a
27:53number of different metabolic disorders.
27:55At the same time, timerestricted feeding
27:57seems to enhance the proliferation of
28:00some of the gut microbiota like
28:02oscillabacttor and some of the other
28:04ones that promote healthy mucosal lining
28:07and that promote better overall
28:10intestinal function. There are some data
28:12that point to differences in the effects
28:14of intermittent fasting for males versus
28:17females. Those data right now only come
28:20from mice. That study was published by
28:22Sachin Panda recently. We still await
28:24the studies in humans. Some people do
28:27not do well on intermittent fasting
28:29either in terms of mood or hormone
28:31health. And so everyone needs to
28:33determine for themselves whether or not
28:34having a timerestricted feeding window
28:36is good for them, how long that
28:38timerestricted feeding window should be.
28:40I think 8 hours is kind of a nice
28:42minimum to adhere to based on everything
28:44that we've covered today. And for some
28:46people, timerestricted feeding is not
28:49going to be compatible with hormone
28:50health for them. For them, eating more
28:53meals spread throughout the day,
28:54presumably smaller meals, same caloric
28:57intake is going to be more beneficial
28:59for their hormones. This is something
29:00that is going to be individual and is
29:02going to have to be determined on an
29:04individual basis. However, if you're
29:05going to try timerestricted feeding, I
29:08do want to remind you that taking a
29:10period of 3 to seven or ideally 10 days
29:12to transition into it, not just going
29:14flipping from eating to three meals a
29:16day that span from 6:00 a.m. to 10 p.m.
29:18and suddenly going to an 8 hour feeding
29:20window, but rather winnowing down that
29:22feeding window about an hour or so per
29:25day is going to allow the hormone
29:27systems of your body, including leptin,
29:29the hypocritein system, which are
29:31systems within the body that signal to
29:32the brain that food is about to come.
29:34Allowing those systems to adjust so that
29:36you're not overwhelmingly hungry,
29:38irritable, and you're not throwing your
29:40whole hormone system out of whack. I
29:43keep coming back to this 8 hour feeding
29:44window, and I want to provide a little
29:46more basis for it. And just to encourage
29:48that it's not completely arbitrary,
29:51there's a particular study that I'd like
29:53to highlight mainly because I don't
29:54expect people to delve into the full
29:56reference list of the other review. And
29:58this is a study that was carried out
30:00between Sachi and Panda's lab and
30:02Christopher's lab. So this is a
30:04collaboration. The study was carried out
30:06in humans and is entitled effects of
30:08eight-hour timerestricted feeding on
30:10body weight and metabolic disease risk
30:12factors in obese adult Adults. Excuse
30:14me. And this study essentially showed,
30:18I'll just read the conclusions,
30:20that an 8-hour timerestricted feeding
30:23produces a mild caloric restriction and
30:25weight loss
30:27without calorie counting. So that's key,
30:30right? These people aren't calorie
30:31counting. Somehow just by adhering to an
30:338 hour window, they are
30:36taking in fewer calories than they're
30:39burning off. And clinically, it reduced
30:42blood pressure. So, I mentioned this
30:44study not because there aren't many
30:45others involving the 8-h hour feeding
30:47window also in humans, but because the
30:498-h hour feeding window has been tested
30:51in obese adults and non-obese adults,
30:53and there are even a few studies in
30:55children. So, this 8 hour window seems
30:57to be a really good rule of thumb and a
30:59kind of anchor around which we can each
31:02think about incorporating timerestricted
31:04feeding. Any discussion about fasting
31:07would be incomplete without a discussion
31:09about what does and does not break a
31:12fast in so far as the scientific
31:14literature says. Drinking water will not
31:18break your fast.
31:21Drinking tea will not break your fast.
31:23Drinking coffee, provided it is black
31:25coffee, will not break your fast.
31:27Ingesting caffeine in pill form, will
31:30not break your fast. There are other
31:32things that won't break your fast. For
31:34instance, eating one peanut when deep in
31:36a fasted state will not break your fast.
31:39However, if you just finished a meal
31:41that included carbohydrates or it was a
31:43very large meal of any kind an hour ago,
31:47yes, indeed, eating one peanut could
31:49break your fast. So, it's all
31:51contextual. That's what's really
31:53important to understand. And unless
31:55you're going to wear a continuous
31:56glucose monitor and set an absolute
31:59numerical threshold for what it is to
32:01break your fast, I think there are some
32:04simple rules that we can follow.
32:07First of all, anything that involves
32:10sugar, in particular, simple sugars, can
32:12potentially break your fast. For
32:14instance, if you drink a can of soda
32:16pop, unless you just ran an
32:18ultramarathon, you're breaking your
32:20fast. Okay? Eat a piece of pizza, you're
32:22breaking your fast. So you can start to
32:24see where there's a lot of wiggle room
32:26and it's very contextual. Today we've
32:28really bypassed the discussion about
32:32foods of a particular origin or type,
32:35animal-based or plant-based, but all the
32:37same rules apply within this thing that
32:40we're call intermittent fasting or
32:41timerestricted feeding. So what breaks a
32:43fast will depend and what you want to
32:46eat or what you are willing to eat,
32:48that's a totally separate manner from
32:50when you eat. But as we've established,
32:53when you eat is vitally important. There
32:55is one particular thing that one can
32:57ingest that can help manage
33:00psychologically and performance-wise
33:03through the fasting portion of the
33:06intermittent fasting and get you to your
33:08feeding window. And that's salt. Many
33:11people find that the kind of
33:13lightadedness, the shakiness that's
33:16accustomed with having slightly low
33:18blood sugar can be offset by taking a
33:22half teaspoon or so of sea salt or even
33:25just a tiny pinch of salt and putting
33:26into some water and drinking it. What is
33:30it doing? How is it offsetting all this?
33:31Well, salt water actually has a mild
33:34effect as a glucose disposal agent, but
33:37it has a stabilizing effect on blood
33:40volume. And so, because sodium brings
33:43with it water and the so-called
33:46osmalerity of your blood and your body
33:48depends on the salt levels in your blood
33:51and brain and body. Many people find
33:54that if they're feeling shaky, they're
33:55feeling lightheaded, they can't
33:56concentrate, they think they need sugar
33:58or food. But what will actually remedy
34:00that is some salt. And all it requires
34:02really is a small pinch of salt.
34:04Ideally, Himalayan or sea salt if you
34:05want to get fancy about it. But table
34:07salt would be fine. In a moment, I'd
34:08like to review the parameters of a ideal
34:12feeding schedule for you and give you
34:15the variables that you can plug into
34:16your lifestyle and your preferences.
34:19So
34:21first of all, you do not want to ingest
34:24food for at least I want to emphasize at
34:26least 60 minutes post waking up.
34:30Second,
34:32you want to avoid ingesting any food for
34:35the 2 to three hours prior to bedtime.
34:39Remember that the sleep related fasting
34:43is especially important
34:45because of all the cellular repair
34:47processes that occur in the liver, in
34:49the gut, in the microbiome, in the
34:51brain, all over the body. And because of
34:54the way that that coordinates the
34:55expression of the clock genes that are
34:57then going to wick out and have many
34:59other positive effects on health,
35:02including weight and fat loss, but in
35:06addition to that, liver health, etc.
35:09An 8-hour feeding window as a target
35:13seems to be the best target feeding
35:15window. Shorter feeding windows of 4 to
35:186 hours tend to lead to overeating and
35:21potentially increases in weight. Regular
35:24placement of the eating window
35:27or feeding window every 24 hours is
35:30important. You don't have to be
35:32absolutely rigid and neurotic about
35:34this, but you don't want it sliding
35:36around on the weekend so that it's
35:37starting two hours later and ending two
35:39hours later a couple days a week because
35:41then you start to offset many of the
35:44positive health effects that have been
35:46demonstrated for timerestricted feeding.
35:50When should that 8 hour window be placed
35:53within each 24-hour cycle? Well, let's
35:55talk about ideal. Ideal, if you really
35:58want to maximize all the health benefits
36:02of timerestricted feeding,
36:06you need to extend the fast around sleep
36:09on both sides. You would place it smack
36:11dab in the middle of the day. It would
36:13be a schedule in which you started
36:15eating, for instance, at 10:00 a.m. and
36:18you stopped eating at 6:00 p.m. An
36:21absolutely dreadful schedule for anyone
36:23that wants to have some semblance of a
36:25normal life. In my opinion, it's not
36:28really compatible with most schedules,
36:30although some people might be able to do
36:31it. Of course, you have to take into
36:33consideration when you exercise. If you
36:36exercise, for instance, I like to
36:38exercise early in the day. If I run or
36:41if I do some moderate or light intensity
36:43exercise, regardless of what type of
36:45exercise it is, I have no trouble
36:47waiting until my feeding window kicks in
36:50around noon or even 2 p.m. But if I do
36:52highintensity weight training, for
36:54instance, early in the day, or if I run
36:56sprints and I do that at 7:00 a.m. or
36:588:00 a.m., by 11:00 a.m. I am very, very
37:01hungry and it's hard for me to do other
37:04things, concentrate, etc. If you're one
37:06of these people or you're somebody who
37:09really is trying to emphasize
37:10hypertrophy or maintenance of muscle,
37:13then it does seem that ingesting protein
37:15early in the day is beneficial that it
37:19can be more readily converted into
37:21muscle tissue. Another thing that we can
37:24add to this summary or key points
37:25related to timerestricted feeding is the
37:29use of glucose disposal agents andor
37:31behaviors.
37:33If you find that you've eaten too close
37:34to a period of time in which you would
37:37prefer to be fasting, that's when a 30
37:39minute brisk walk or even modest walk
37:42after eating can be beneficial. And then
37:46there are the things like metformin and
37:47bourberine. And I mentioned earlier why
37:50you would want to approach those with
37:51the appropriate level of caution and
37:53figure out the dosages for you. And for
37:55some people, the dosages will be zero
37:57milligrams is going to be ideal. I know
38:00we covered a lot of information today. I
38:02hope you learned a lot about
38:03timerestricted feeding. I hope you
38:05learned a lot about metabolism and
38:08energy and health and how when you eat
38:11is as important as what you eat. And
38:13last, but certainly not least, thank you
38:15for your interest in science.
38:20[Music]

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