Dive deep into the fascinating world of Intermittent Fasting, where we explore the Hormonal Model and the Carbohydrate Insulin Model, revealing the secrets behind this popular health trend
Jason Fung
⏰ Cracking the Code: The Science of Intermittent Fasting 🍽️ Dive deep into the fascinating world of Intermittent Fasting, where we explore the Hormonal Model and the Carbohydrate Insulin Model, revealing the secrets behind this popular health trend. Discover the intricate relationship between calories in and calories out, and what the ‘Biggest Loser’ study teaches us about long-term weight management. 🔬 Uncover the science of Feeding and Fasting and why it’s not just about counting calories. Hormones vs. Calories – which matters more in your health journey? We break it down. 🌟 Explore the ultimate and proximate causes of how Intermittent Fasting impacts our bodies at the cellular level, and why it’s not just about dieting. 🍴 Learn how fasting affects hunger, metabolic rate, and even how doctors are embracing these principles to lose weight and improve health. Plus, we’ll delve into the concept of Time Restricted Eating and its benefits. Join us as we unravel the science of intermittent fasting, its impact on hormones, metabolism, and overall well-being. Hit the like button 👍, subscribe for more enlightening content, and ring the notification bell 🔔 to stay informed! 👉Join my membership for perks: / @drjasonfung ▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
▶️ Timestamps / Chapters 0:00 Outro 2:22 Hormonal Model 3:13 Carbohydrate insulin model 9:12 what’s the relationship between calories and calories out? 14:42 The biggest loser study 16:46 Feeding and fasting 21:29 Hormones vs Calories 26:05 Ultimate vs proximate causes 27:27 Cell metabolism 35:17 How does fasting affect hunger? 37:17 Metabolic rate 40:02 How Do Doctors lose weight? 42:41 Time Restricted Eating 48:51 Outro ============================= 📌 BOOKS: 👉 The Obesity Code – Reviewing underlying physiology of weight loss and how low carb diets and fasting can help. https://www.amazon.com/dp/1771641258?... 👉 The Diabetes Code – Reviewing how type 2 diabetes is a reversible disease and dietary strategies. https://www.amazon.com/dp/B0795BLS8D?... 👉 The Cancer Code – Scientific exploration of how cancer develops – https://www.amazon.com/dp/0062894005?... 📌 Amazon: 👉 USA – https://www.amazon.com/shop/jasonfung 👉 Canada – https://www.amazon.ca/shop/jasonfung ▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
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📌 YouTube Medical Lectures (for specialist physicians): ▶️ The Roots of the Obesity Epidemic: https: // • The Obesity Epidemic, Explained ▶️ Therapeutic Fasting – The Two Compartment Problem: https: // • Fasting and Weight Loss – Solving the… ▶️ Does Calorie Counting work?: • Why Calorie Counting rarely leads to … ▶️ Two Big Lies of Type 2 Diabetes: • Two Big Lies about Type 2 Diabetes
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Transcript:
0:03[Music]
0:13thanks for having me here I’m really excited to be here it’s uh you know it’s
0:18always exciting to be back at Live Events so today I’m going to talk about a little bit about the physiology of
0:25sort of weight gain and how intermittent fasting can help play a role for your patient
0:31um so as mentioned I did uh write a few books I’m also a consultant for level two which is focused on trying to
0:37reverse type two diabetes and today what we’re going to discuss is the physiology of fasting
0:43sort of weight gain obesity and then review a recent trial that uh you know
0:49that that may have uh questioned it a little bit and then understand what sort of advantages fasting might offer for
0:56your patients so the real question here is there’s
1:02always this little tension between sort of this uh models of weight gain so this
1:08is the calories model and the idea is that food contains energy and you
1:13measure that food energy as calories and some people believe that really that’s
1:19all you need to know about weight gain a calorie is a calorie you hear that all the time and the idea is that all
1:26calories are equally fattening right because if you eat 100 calories of broccoli it’s just as fattening as 100
1:34calories of cookies and that’s the idea that’s behind most of the way we were
1:40trained if you look at even very recent uh guidelines this is from 20121 you can
1:46see that their number one sort of advice for weight loss is adjust energy intake
1:52and expenditure so energy intake of course is calories in calories out in
1:57other words the standard advice of eating less and moving more with the
2:02second sort of implicit assumption that all of this is under your control you
2:08have Direct Control of what you eat you have direct control of your exercise therefore weight gain is really up to
2:14you and it’s all about those calories and this is found in almost all I have that in the kigo guidelines which is the
2:21nephology guidelines but there’s another uh sort of idea that’s uh sort of a
Hormonal Model
2:26hormonal model which is similar but a little bit more inclusive that is yes
2:32food contains energy but it also contains information that is the
2:37response to what we eat is different we know that that’s just a fact if you eat
2:43cookies for example your insulin is going to go way up your blood glucose is going to go way up if you eat salmon or
2:49an egg with no carbs for example it’s not going to go up and those hormones
2:54are instructions as to what our body is supposed to do and both of these these
3:00are important so you really have to look at both the calories and sort of the quality of those calories or what those
3:06calories are composed of because they elicit different hormonal responses and
3:12this this is uh written again in 2021 by a lot of researchers including very
Carbohydrate insulin model
3:19prominent ones such as David Ludwig from Harvard and uh Walter wiet from Harvard so very prominent nutrition and and
3:26they’re talking about this carbohydrate insulin model so the main hormone we’re talking about is insulin and we’re worri
3:33you know we care about insulin for the main reason is that we know that it breaks down it stops the breakdown of
3:41glycogen and body fat and increases the synthesis of the glycogen body fat that
3:46is it’s a storage hormone you increase glycogen synthesis you increase denovo
3:52lipogenesis and you stop glycogenolysis and lipolysis that’s just what it does
3:58we we’ve known that for many years so what they’re saying is that it’s the hormones that are really important in
4:03addition to the calories so it all sort of stems back to this model which is the
4:08energy balance equation which is that body fat equals calories in calories out and this is the main thing that people
4:14talk about when they say oh you have to drive this caloric deficit but the one thing you have to realize is that a
4:20caloric deficit never exists you cannot ever have a caloric deficit this is a balanc equation so if you are looking at
4:28this you have three things you have body fat you have calories in and calories out so if you uh change one there are
4:36two other variables that have to balance there’s never a deficit it’s always a balanced
4:42equation so when you talk about people who just say well just eat less and you’re going to lose weight this is this
4:48is what they’re talking about they say well if you eat fewer calories then you’re going to have a lower body
4:55fat because of the first law of thermodynamics and so on what they’re assuming is that the metabolic rate or
5:01your calories out stays the same that’s not necessarily true because the first
5:07law of thermodynamics doesn’t say that you’re going to lose body fat remember there’s three variables so if you simply
5:14reduce the variables in calories in you could just as easily balance that
5:20equation by keeping body fat the same and lowering your metabolic rate that is
5:25you reduce calories in and your body Burns less calories and body fat stays the same so it doesn’t break the laws of
5:32thermodynamics which is one of the things that people always say well just eat less you’re going to lose weight no
5:38not necessarily it makes no such statement at all it’s a complete misunderstanding of the laws of
5:43thermodynamics so the question is what happens in real life if you eat fewer
5:49calories do you lose body fat or does your metabolic rate go down well the first studies of this uh
5:58happened in the 1900 hundreds so this was a study in 1944 by Dr anel keys and
6:04it was called the biology of human starvation and it was brought on because they wanted to know what happens to the
6:10human body if you don’t have enough to eat this is World War II so they put people on a 40% uh reduction in calories
6:18and they were eating 1570 calories per day which doesn’t actually seem so bad and it was mostly starchy sort of low
6:25protein lowfat foods because this is what was available in war torn Europe at the time so again lowfat Foods this is
6:32actually pretty close to what we tell people to eat 1500 calories lowfat foods
6:38and um what happened well when they measured the metabolic rate what they found was that their metabolic rate
6:45actually dropped by 40% so these people their their heart volume strength their
6:51heart rate slowed their body temperatures went down so what they felt was they felt cold they felt tired they
6:59you know just felt terrible because their bodies weren’t getting the energy that they needed to uh run all the
7:07organs you know your heart and your liver and your brain and all that sort of stuff and generate body heat but the
7:12bottom line is that if you simply reduce calories your body has this other option of reducing the calories out and this is
7:20obviously true because if you think about it there is no possible way that your body cannot adapt it’s basic
7:26homeostasis if you say okay eat 5 00 calories less per day you’ll lose a pound a week does that mean if you weigh
7:33200 lb in 200 weeks you’re going to weigh zero well obviously not so at some point your body has to adapt it turns
7:41out it adapts almost immediately so this is uh again in 1971
7:49so 50 years ago they did very much the same thing where they did underfeeding and what they showed was that if you
7:55underfeed somebody their metabolic rate goes down so 10 to 20% reduction in your metabolic rate and
8:04this is shown again and again so this is The Biggest Loser study where it’s an American reality series and they
8:11basically were competing to lose weight and what they found is that as they lost weight the metabolic rate just kept
8:17going down and down the diet of course was a calorie restricted diet and even though they tried to make up for this
8:24decreasing metabolic rate with more exercise at some point they weren’t able to keep up exercise and and it didn’t
8:31really affect the metabolic rate because how much you exercise doesn’t affect your metabolic rate remember when you’re
8:37exercising you’re going to exercise your skeletal muscle but you’re not exercising your liver you’re not
8:43exercising your lungs you’re not exercising your kidneys so the amount of energy that it’s using is is is not
8:50changed and it’s going down as you eat a calorie reduced diet so this is this is
8:57sort of well known even by 1991 one so 30 years ago they did a met analysis of
9:0229 studies basically all showing the same thing what is the relationship
9:07between caloric restriction and change in resting metabolic rate remember
what’s the relationship between calories and calories out?
9:13that’s your calories at what’s your relationship between calories in and calories out and you can see that almost
9:19all of them show a decrease in metabolic rate of between 10 and
9:2420% so their conclusion is that the first statement which can be made with
9:30some certainty is that a decrease in energy expenditure is a universal
9:36response to energy restriction in other words if you just eat less your body is just going to burn
9:43less which is going to keep body fat relatively unchanged and that’s exactly what we see
9:51clinically that’s exactly what we see so then the the the sort of flip side is
9:56what if you just exercise more that’s going to make lose weight right and again people say well if you increase
10:03the calories out you’re going to lose body fat it’s just the first law of the Dynamics but again it’s not there’s
10:10three variables so you can change your body fat which would be great or
10:15alternatively your body fat could stay the same and you could simply eat more so increase calories out maybe you
10:22increase calories in and that’s going to negate any benefit in terms of body fatness and again it doesn’t break any
10:29laws of thermodynamics so anybody who says you know it’s breaking the laws of thermodynamics doesn’t actually
10:34understand physiology because there are three variables so the question is what
10:39happens when you exercise well they did a met analysis this was very recent from 2021 and they did all these sort of
10:47exercise training interventions on and and what effect does it have on energy
10:52intake so they included 48 studies but a lot of them were very poor quality so when they threw most of the poor quality
10:58out ones they uh were left with these studies and when you sort of put them all together in a metaanalysis what you
11:05find is that when you exercise you are left with an increase in hunger and if
11:11you’re hungrier you’re going to eat more that’s just a natural thing and that’s
11:16why they say you work up an appetite they don’t say it for no reason during acute exercise your appetite goes down
11:22when you’re playing soccer or something you don’t go wow I’m really hungry because you’re busy but afterwards
11:28that’s when you start to feel and that increase in hunger is going to naturally lead to an increase in
11:33calories in and that’s how you get results like this and this was done at Harvard and they looked at the sort of
11:40estimated energy gap so when you do certain activities are you going to be positive calories or negative calories
11:47so this is watching TV so you take kids you have them watch TV and you calculate how much energy is going in how much
11:53energy is going out and they’re actually positive 100 calories per hour so that’s that makes sense you watch TV you gain
11:59weight well that’s almost the exact same as when you do mild
12:05exercise when you do mild exercise the overall net effect is positive 99
12:12calories per hour it’s not going down you’re not losing weight because you’re in a
12:17positive energy balance and it’s because you’re hungry that’s the only way you can do it because the actual exercise of
12:24course doesn’t lead to weight gain and even uh playing video games is positive
12:29that makes sense but you have to get this sort of moderate exercise before you’re neutral and then if you get to
12:37very intense exercise then you can start to get negative but this sort of oh just do a little bit of exercise it’s not
12:44really very effective advice and it doesn’t break any laws of thermodynamics and there’s one other
12:50thing in terms of calories out which is that it’s not just the exercise but your metabolic rate so your calories out is
12:57two things if you increase your exercise you might get more hungry but the other
13:02thing that might happen is your metabolic rate may go down to compensate so this is a model which we
13:10all think happens which is the standard model here which is the additive model
13:15on the left and what that says is that you have a baseline sort of uh metabolic
13:21rate and you simply add the exercise and the more exercise you do the more energy you expend there’s another theoretical
13:28model which is the constrained model which is that at some certain point any additional exercise is simply going to
13:35be matched by a decrease in your resting metabolic rate and what they did here
13:41and this was again fairly recent 2016 they they measured exactly that what
13:47happens with exercise and they use doubly labeled water they use five populations of 332
13:53adults which is it is it the additive model which we think it is or is it this constrained model and it turns out it’s
14:00constrained so if you look at total energy expenditure on this uh x-axis
14:07compared to the amount of physical activity what you find is that after a certain point you don’t get any more
14:14total energy expenditure that is any additional expenditure that you’re getting with exercise is going to be
14:21matched so that the line goes flat you can’t expend more energy after a certain
14:26point that it it just doesn’t happen so the body always adapts we it’s it’s you
14:32know the basic principles of life is homeostasis and this is what happens there’s a certain point where the the
14:39slope becomes zero and again looking back at this bigger biggest loser study
The biggest loser study
14:45this is from 2021 when they went back and they said okay we know that these people with using this calorie
14:52restricted diet and increased exercise we know that their metabolic rates went down let’s compare that to how much
14:58exercise they got well the people who did less exercise dropped their
15:03metabolic rate but the people who did more exercise drop their metabolic rate
15:08more so again that’s your heart your lungs your kidney your brain all using
15:14less energy so even though you’re doing more exercise more skeletal muscle activity you’re it’s being matched by a
15:22decrease in body generation so there’s a point where you actually don’t get any net benefit even in terms of energy and
15:30this is uh the idea if you simply eat fewer calories which is our basic sort
15:37of you know advice it doesn’t necessarily lead to lower body fat
15:43because there’s an alternative your body can either you know lower the body fat
15:49or it can lower its expenditures and which one it does has a critical role in
15:55how much body fat you carry and of course that is ultimately determined by the hormones same thing with exercise
16:02if you exercise more it doesn’t necessarily lower body fat it could in an ideal world but you could just eat
16:10more or your metabolic rate could go down and again which one happens again
16:15depends on hormones so ultimately it all depends on hormones because our whole
16:20body runs on hormones you know our body has no calorie receptors right there’s no cell receptor that says oh here’s a
16:28calorie this is what I’m going to do our body runs on hormones those are instructions as to what to do how how
16:35much to pump blood how you know how much body heat to generate everything in our body is run on hormones not calories so
16:42ignoring the hormonal side of things is not a great idea so if we think about feeding and fasting this is sort of what
Feeding and fasting
16:50happens it’s not just about calories so this is the calories going in so it’s
16:56like energy it’s food energy that’s all it is so I’ve to pict it here like coal in a coal burning power plant for
17:02example when you eat you’re eating calories your body senses this because
17:07insulin goes up and insulin is a nutrient sensor it tells your body hey food is coming in this is what you need
17:13to do so you store some of it right so you generate sugar like glycogen right
17:19sugar glucose molecules they string them all together stick them in the liver that’s glycogen that’s glycogen
17:25synthesis if you have more glycogen then and you generate body fat which is
17:31denovo lipogenesis um and that’s one option the other option is you burn it so for
17:36metabolic rate for exercise what you can’t do is you can’t take stored fat or
17:43sugar and burn it because we know that insulin inhibits lipolysis remember insulin is a nutrient
17:50sensor it’s telling your body store this energy that is coming in you don’t want to burn your stores you want to put more
17:58in right you can’t put stores in and take stores out at the same time that’s just working against yourself so insulin
18:05is going to tell your body go in so what you cannot do when insulin is high is burn body fat that’s just basic and this
18:12is again just you know we’ve known it for a long time just just one of the most basic functions of insulin is to
18:17inhibit lipolysis it’s only when insulin starts to fall that you disinhibit the
18:25lipolysis then you can break down your glycogen which is glycogenolysis right you take the glycogen which is chains of
18:32glucose you break it all up throw that glucose back into the blood and you have a source of energy that’s the reason you
18:37don’t die in your sleep every single night but it depends on this insulin falling to get that back out or if
18:44there’s not enough glycogen then you break down triglycerides and use it as a source of energy so you take your stores
18:50and you burn it but that depends on the insulin falling one of the ways you can do that of course is fasting that’s how
18:56you’re normally supposed to do that so as insulin Falls remember other hormones
19:01go up and these are the counterregulatory hormones these are going to take energy from it stores and
19:08push it back into the blood and this includes the sympathetic nervous system so mediated by the vagus nerve nor
19:14adrenaline growth hormone and cortisol all of these are basic counterregulatory
19:19hormones and they all go up as insulin starts to fall and that’s going to have an effect because if you are going to
19:25stimulate the sympatic nervous system by nor adrenaline well your metabolic rate is going to
19:31stay more stable because you’re stimulating the system So that’s its basic function is
19:37to take the energy out so if we think about weight loss we think about these three variables let’s think about how
19:43we’re trying to lose weight if you simply restrict the calories but you’re keeping your insulin levels very high
19:50you’re eating lowfat food so high carbohydrates you’re eating constantly from the minute you get up to the minute you go to bed insulin is going to stay
19:56up so in a steady state you’re going to have 2,000 calories going in 2,000
20:01calories coming out now you want to lose weight so you reduce it by dropping it
20:07to, 1500 calories per day well insulin stays High you still have 2,000 calories
20:13here so you’re not imbalance you cannot have an imbalance so where are you going
20:19to get the extra 500 calories from well you can’t get it from your fat stores
20:24because your insulin levels are pumped up really high so the only possible way
20:29you can balance this equation is to drop your metabolic rate which is in fact
20:36exactly what we’ve shown in our research for the last 50 years compare that to
20:41the same calories but you’re going to use say an intermittent fasting strategy where you’re going to allow the insulin
20:47levels to fall so again you’re going to start with 2,000 calories in 2,000 calories out you’re going to reduce your
20:54calories to, 1500 because that’s what you’re trying to do but in this case you’re going to allow your insulin
20:59levels to fall so what happens is that you simply take those 500 calories out
21:05of storage and use them now you’re perfectly IM balance your metabolic rate
21:10never had to drop because you’ve opened up the storage facilities that’s what
21:15insulin does that’s its whole job it’s not necessarily good or bad that’s its job is to keep it in storage if you
21:22haven’t kept it in if you if you are opening up that sort of storage door you can take it out
Hormones vs Calories
21:29so the question is which one is sort of more powerful and this is a very interesting study done a few years ago
21:35where you said well let’s think about these hormones versus the calories so let’s keep the insulin levels high but
21:41reduce our our calories what’s going to happen well if you believe all in the calories in calories out model you’ll
21:46say well you’re going to lose weight because you reduce calories as opposed to the hormonal model which is going to
21:51say well you’re going to gain weight because insulin levels are high and that’s the main driver of weight gain
21:58because our body runs on hormones so this is the study they did it in type 2 diabetics and basically at Time Zero
22:05they were on zero insulin over six months they bumped up the insulin to a 100 units a day so quite a lot and at
22:13the same time they reduce the calorie intake from about 2,000 calories to 1,700 calories so 300 calories per day
22:22less so you’re going to expect over six months a significant weight loss if it’s all about calories so what actually
22:29happened which shouldn’t be a surprise to anybody who’s prescribed this is that they gained 20
22:35pounds even as they reduce their calories so it wasn’t never about
22:42calories in calories out the insulin is telling your body hey store this calories as fat so therefore the rest of
22:49the body simply has less energy to burn that’s the only way that you can actually gain weight while eating fewer
22:57calories so in in the whole scheme of things both calories and hormones are
23:02very important you shouldn’t focus on calories and ignore the hormones and you shouldn’t focus on hormones and ignore
23:08the calories and the main hormone we have to think about is insulin so intermittent fasting is probably the
23:15most efficient way to get your insulin levels down because you’re eating zero and you can’t get lower than zero low
23:22carbohydrate diets are going to come very close um but it’s not going to come as close as fasting but you what you
23:28shouldn’t do is sort of say oh I’m going to fast but then I’m going to eat whatever I want cuz if you simply fast
23:34and then overfeed you’re you’re getting the hormone part right but you’re not getting the calorie part right because energy is still part of the part of the
23:42mix there you have to get both right in order to do it so this is the most recent study which was in the New
23:48England Journal of Medicine probably two months ago and what they did was a a a a
23:54calorie restriction with or without Tim restricted eating so um you know so here
23:59here’s a good study right calories or calories plus uh intermittent fasting which is time-restricted eating and so
24:07both of them both groups were calorie restricted and at one year they said well there’s no statistically
24:13significant difference so therefore it’s not really the fasting that’s important it’s all about calories but you have to
24:19look a little deeper into what what they actually uh did here you can see that at uh 6 months it was the the the between
24:26group difference was .5 kilos at a year is 1.8 kilos so the difference is
24:31increasing but it’s not statistically significant so when it’s not statistically significant the first
24:36question you have to ask is well is it just underpowered because there’s an effect there but you don’t it’s not statistically significant so is it just
24:43underpowered and of course the the media went crazy the New York Times and everybody else said well there’s no
24:49benefits to time-restricted eating and the problem is that it really was kind of underpowered because when they did
24:54the power study they calculated that they had to be able to show an extra 2.5 kilogram
25:02difference between the two groups in order for this study to be positive but
25:08if you look at the fasting time they only went from 13.8 hours to 16 hours so
25:14you had a 16% increase in your fasting time given that the control group lost
25:206.3 kilos which is pretty good actually to get an additional 2.5 kilos means you
25:26have to have an additional 40% % benefit so you know if you’re thinking that you’re going to just increase the
25:33fasting Time by 16% and get a 40% difference in weight loss it ain’t going
25:39to happen so it was really underpowered and and that’s the real problem with jumping to the conclusion the study is
25:45the study I think I’m all for studies but you simply can’t conclude that there’s no benefits because the
25:51increased weight loss was only 28% and therefore they said negative but clinically that could still make a big
25:57difference we know that small amounts of weight loss can make huge differences in terms of metabolic Health um the other
26:04problem is that the way they did the study was that when you’re comparing two
Ultimate vs proximate causes
26:10things A and B if they’re independent of each other then you can do a study like that A Plus B versus B alone however you
26:17can’t do that when the study is a causes B which causes C so if you’re keeping B
26:24fixed and then measuring C they’re going to be the same but it doesn’t mean that
26:30this is irrelevant because this is the ultimate cause so you have to treat the
26:36root causes in order to be successful so for example if you have a drug such as
26:41semaglutide which causes you to not eat eat fewer calories and that causes
26:46weight loss well we know it’s a very good weight loss drug that’s that’s been published and so on but it’s the drug
26:54that allows you to have fewer calories if you simply fix the fewer calories calories and show the same weight loss
27:00you can’t conclude that the semaglutide was had had no benefits the benefit was
27:06that it allowed you to eat few calories on a more successful basis and and and it doesn’t mean sagte has no benefits
27:13and that’s exactly the same problem with Tim restricted eating if it’s Tim restricted eating that allows you to eat
27:20fewer calories then that’s still a benefit because you can’t do that so easily by itself and we have many
Cell metabolism
27:28studies that show that if you simply restrict the time that you’re eating you’re going to eat less overall this
27:35study for example which is in cell metabolism they did something very similar they took 4 Hour versus 6-h hour
27:41Tim restricted eating versus control and what they found of course was that without telling people to eat fewer
27:48calories they ate fewer calories so the Tim restricted eating resulted in about a 500 calorie per day uh less without
27:58people sort of knowingly counting calories or doing it so it’s that Tim restricted eating because obviously if
28:04you have less opportunities to eat it’s going to be easier to eat less if your
28:10rule is don’t eat after 6 then you’re not going to be as tempted to go out and have you know some chips or something at
28:16the in the late night because that’s your eating rule so it’s the Tim restricted eating that is is allowing
28:22you to do that the thing is that you always have to think about these ultimate causes because if you say
28:28something like oh well the problem is you have an emotional eating problem which is causing you to eat too many
28:35calories or is causing weight gain you can’t say well that’s irrelevant because that’s your root cause or you’re eating
28:41too much sugar you’re eating too much you know to to out too much or bad habits you always have to treat the root
28:48cause and that’s the most important thing if you’re going to be successful the second
28:53thing is that this is a more comprehensive that is this is why they’re gaining weight but this is why
29:00they’re doing that to gain weight right so you’re going that sort of one level up yes you’re eating too many calories
29:06but why are you eating too many calories maybe you have too much opportunity to eat calories and that’s your problem and
29:13by restricting that time you’re going to be more successful it doesn’t mean that there’s no benefits here I mean just
29:20saying you know treating this is like saying to somebody who’s depressed oh just cheer up like it doesn’t work like
29:27that you always have to understand your root causes and if your root cause is that
29:33you’re having too much time too much opportunity then fix that and that’s what Tim restricted eating does so when
29:39you’re talking about clinical weight loss you know if we take this example where you have you know 2,000 calories
29:45in 2,000 calories out you’re eating breakfast lunch and dinner the idea is not to take more calories the idea is
29:51simply to take this meal and make sure that you’re getting those calories out from body fat and the way you do that of
29:58course is you allow your insulin levels to fall and that’s what’s really important so fasting is really two
30:06things which is a way to eat fewer calories by putting in those restrictions and a way of allowing your
30:12body to get the energy that it needs from its body stores because body fat is
30:18nothing more or less than a store of calories that you ate in the past but if
30:25you close those doors off if you keep insulin High those doors are locked you cannot get that energy back out so the
30:33only way you can get it is to eat more to satisfy your energy requirements think about it this way if
30:38your insulin levels are always high like you see with type 2 diabetes when we pump them full of insulin what happens
30:45is that if you eat a th000 calories all of that’s going to go straight into stores which is body fat then your
30:50body’s like hey I have no energy here I still need to generate body heat go and
30:56eat something and this is why if people who are eating you know in the past these low-fat diets they eat two slices
31:02of white bread with Jam by the time they get to you know 10:30 they’re ravenous
31:08so they’re looking for a low-fat muffin why because your blood glucose spiked up your insulin spiked up all of those
31:14calories that you ate with breakfast went straight into your stores and you have nothing left to to you know to
31:21concentrate to do all your stuff if you ate the bacon and eggs that your you know your grandmother did well that
31:27would would happen because the insulin level is not going so high so this is
31:33exactly of course the hormonal model which is that both energy and the hormones are very important you can’t
31:39ignore one versus the other but really is it is it that because again trying to
31:45think that one step more this is the way we think about energy balance body fat equals calories in minus calories out
31:52well we say well this is your diet this is your exercise It’s all under conscious control so if you’re overweight is your own fault
31:58you made that decision but is it really because let’s think one step deeper why
32:04are you eating too much well maybe you’re just really hungry maybe you’re just hungry all the time because all of
32:10that energy went into your body fat right and it’s not just exercise it’s your metabolic rate and these are not
32:17under your control you can’t decide to be less hungry you can decide not to eat
32:22but you can’t decide to be less hungry you can’t decide to burn more energy in your metabolic rate so in the end what
32:29is controlling your hunger and your metabolic rate because those are your determinant of your diet your calories
32:36in your calories out which is going to drive body fat but this is understanding it at a very superficial level and this
32:44is understanding it at a much deeper level of why so it’s hormones of course
32:49what drives hunger while gellin is the hunger hormone glp1 is a satiety hormone
32:55so if you’re full you’re not going to eat that’s as basic as that that your metabolic rate while your sympathetic
33:00tone your nor adrenaline if you’re pumping up your metabolic rate you’re going to burn more energy so let’s think
33:05about the things that we know cause weight gain and weight loss well the
33:11insulin we know insulin causes weight gain this is from the dcct trial and they gave type 1 diabetics a lot of
33:17insulin versus sort of less insulin and yes the people who got tight glucose
33:22control with a lot of insulin did better but how many gained weight well like at the end of the trial almost 30% had
33:29major weight gain so we know insulin causes weight gain anybody who’s taken
33:34it or has prescribed it has got patients come back and say man I just gained like 30 pounds we’ve all had that experience
33:42and is it a calorie agent or is it a hormonal agent well obviously it’s a hormonal agent it’s the hormones which
33:49Drive the behavior we know gp1 Agonist are very successful at Weight Loss this is that
33:56trial from the New England Journal of medic about a 17% weight body weight loss that’s a
34:02huge percentage well is it a caloric agent are you counting calories not at
34:07all counting calories just doesn’t work we’ve tried it it has doesn’t work what it does of course is it makes you not
34:14want to eat because you’re nauseous so you don’t eat and guess what you lose
34:20weight but it’s a hormonal agent what you’re doing is affecting the hormones not the calories nicotine so nicotine
34:29causes weight loss this is this is the people who smoke so you see that they’re much lower than the people who don’t
34:35smoke and this is the people who quit so when you quit you gain weight and is
34:41nicotine a caloric agent not at all does has nothing to do with calories in fact it’s a hormonal agent it affects you
34:47multiple levels but noradrenaline and norepinephrine is one of the major things so it’s a sympathomimetic it
34:53increases your metabolic rate at the same time it has effects on gapa pentin
34:59and so sorry The gapa receptors to decrease appetite and increase satiety so people who smoke just aren’t as
35:04hungry at the same time they’re bumping up their metabolic rate so therefore they’re going to lose weight and they
35:11sustain it you see that they sustain it when you quit you gain that weight right back but it’s a hormonal agent so the
How does fasting affect hunger?
35:17two things that are going to drive your uh weight gain is hunger and metabolic
35:22rate forget calories and calories out because that’s a very superficial understanding you have to understand hunger are you more hungry if you’re
35:29more hungry you’re going to eat more well how does fasting affect hunger well this is gellin so gellin is a hunger
35:36hormone and you can measure it if you fast so this is a study they fasted people over 24 hours and they measured
35:42gillin so they have three spikes most people have three spikes lunch dinner and breakfast the interesting part is
35:48what happens if you don’t eat lunch for example so you’re busy you’re in you know the O you’re busy you miss your
35:55lunch you’re hungry but what happens is that gellin actually falls right back down to Baseline so by 4:00 you’re
36:03actually equally as hungry as if you had eaten what happened well your body just took the calories it needed from its
36:10stores that’s all same thing at dinner you skip dinner you’re hungry yes but
36:15then when you don’t eat your hunger actually just Falls right back down to Baseline you’re know more hungry than if
36:22you ate you are more hungry immediately but if you give it time that passes because you’re going to get your uh
36:29energy from somewhere else this is over multiple days of fasting what you see is that you get this up and down but over
36:37two three days four days gin actually starts to go down the P the the effect
36:43on gellin in terms of uh clinically this is a study which they compared caloric
36:49restriction versus alternate daily fasting and when you measure gin what you see is that this is a P value of 048
36:56so significantly different those people who just did caloric restriction increase their grin which means that
37:02they are more hungry so if you’re just restricting calories you’re more hungry it’s not some psychological Voodoo thing
37:09they are physiologically more hungry an effect that you do not get with the alternate daily
37:16fasting if you look at metabolic rate again what’s going to determine that well people say well if you’re going to
Metabolic rate
37:22fast you’re going to you know go into starvation mode your metabolic rate’s going to go down well this is what actually happens you take people and you
37:29measure them and you fast them for 4 days at day zero this is their their weight it’s steadily going down this is
37:36their resting energy expenditure so how much they’re burning and this is their V2 so the amount of work that they’re
37:42actually doing so after 4 days of not eating what you see is that they’re burning about 10% more calories than
37:51they did at a zero your body is not shutting down it’s ramping itself back
37:56up and again why it’s basic physiology your sympathetic tone has gone up your
38:02nor adrenaline has gone up and that’s why interestingly enough growth hormone has also gone up which is very
38:08interesting because you think why is growth hormone going up well again when you start to eat you want that growth
38:13hormone up so that you are able to maintain your lean mass this is again another study looking at human adapost
38:20tissue after 72 hours of fasting so this is noradrenaline so
38:25noradrenaline is just pumping itself up that’s the effect and so when you look at resting energy
38:34expenditure what happens how much energy are you burning you’ve gone from 1684 to
38:391729 after 3 days of no food you’re burning more energy than on day Zero so
38:46this whole idea that oh you’re going to kill your met metabolic rate is actually completely false because if you
38:53understood the hormonal effect of fasting you would say No it should be the exact opposite you should be going up and that’s what all our physiologic
38:59testing is showing and once again that’s this is that study comparing 32 weeks of alternate daily fasting versus calorie
39:06restriction and again you see calorie restriction with a P value of .045 means
39:11that they have dropped their metabolic rate they’re burning about 76 calories less per day with calorie
39:17restriction first is the alternate daily fasting which is the P value of 04 not significant so if you’re just trying to
39:25do calorie restriction you’re going to be more hungry so you’re going to increase your calories in at the same
39:32time you’re going to be burning fewer calories because your resting metabolic rate went down what’s that going to do
39:38to body fat well you know you just have to look at the energy balance equation increase calories in lower calories out
39:45you’re going to gain body fat through calorie restriction and of course this
39:50is the standard advice we’ve been giving for 50 years the one that’s been so unsuccessful if you want to be
39:57successful you have to be able to decrease hunger and increase metabolic rate so this was a very interesting
How Do Doctors lose weight?
40:03study of how do doctors lose weight so they took a poll of 900 female doctors
40:08and said what do you use to lose weight and what do you tell your patients and these people were pretty successful
40:14actually so they weren’t that overweight but uh you know body mass index of 24.9
40:19and they were able to lose 13.2 lbs on average what did they do well 75% of
40:27them use intermittent fasting they didn’t tell their patients to do it like 25 30% but they did it for
40:34themselves why because if you want to lose weight you’re not going to go for that strategy that just doesn’t work
40:41you’re going to go for the stuff that works which is intermittent
40:47fasting there is another question about eating disorders so this is very important of course there’s always this
40:52question that hey if you’re going to diet or if you’re going to fast are you going to increase hunger and therefore
40:58leave people susceptible to eating disorders the other issue is that you may decrease tryptophans which is a
41:04precursors for serotonin and leave people sort of dymic a little bit depressed and therefore prone to eating
41:09disorders there’s been several studies to look at this and this was uh one of the most important ones which is uh does
41:16short-term fasting promote eating disorders and this was 218 participants
41:22and they did a 24-hour fast and they monitored them for disordered eating and basically their conclusion was no it
41:28does not significantly predict increase in Eating Disorders uh this was another
41:34trial in 2000 and they took people with actual diagnosed eating disorders and
41:39said well if you fast them do they get more and again the answer was no he said
41:45a period of acute food deprivation did not trigger eating eating pathology and
41:50this one the same thing what happens when you give an acute fast do they eat a lot more afterwards and the answer was
41:57no no even a 36-hour fast did not induce a powerful unconditioned stimulus to
42:03compensate that is if you don’t eat for 36 hours you eat a little bit more but you’re not completely uncontrolled which
42:10is the the problem with eating disorders so essentially the food contains food contains energy which is
42:18calories and also information which is the hormonal response and the fasting is just a very efficient way to eat fewer
42:25calories at the same time allow the hormones that allow body fat loss and
42:33the reason it does is because it tends to reduce the hunger and increase the metabolic rate which is exactly the
42:39opposite of the standard advice we give people so whereas the New York Times is telling people that Tim restricted
Time Restricted Eating
42:45eating has no benefits it’s actually completely untrue because the whole
42:50point of time-restricted eating is that you’re going to create a structure to your eating day that is you eat eat
42:57between this hour and this hour outside of that don’t eat that’s a very simple rule that everybody can follow as
43:03opposed to hey eat all the time whenever you want but count the calories well you
43:09have no idea how many calories are in your food if you’re eating whole unprocessed foods like we tell everybody
43:16to do they don’t come with calorie uh counts you eat a piece of steak well you
43:22have no idea how much it is it’s a completely nebulous rule it’s completely a you have no idea nobody has any idea
43:29when they do studies of calorie counting every single person is off by a lot as
43:34opposed to simply saying don’t eat between this hour and this hour now you have a structure that you can be
43:40successful at because it’s very simple to follow this builds dietary consistency because if you’re going to
43:46do this breakfast lunch dinner nothing after dinner well you’re going to build consistency and consistency is going to
43:52build habits why is that important because habits don’t require will power
43:58if you’re in the habit of not eating after dinner it’s not difficult to not
44:03eat after dinner because that’s what you always do that’s the point you want to build consistent dietary habits so that
44:10you can be successful without doing anything because that’s just your Baseline it’s a very easy way to reduce
44:17calories because you’re counting hours of the day which is very simple and hard versus calories which is very hard to do
44:26and it’s simply a traditional way of eating you’re supposed to have a period
44:31of time that you eat and a period of time that you don’t eat where you are going to digest those calories that’s it
44:38so the simplest rule of weight loss is just don’t eat all the time it’s not going to work and if you look at the
44:45advantages of fasting to your patients there’s a huge number of them you don’t
44:50have to use it but fasting is just a tool for you to use it’s it’s like anything else it’s like you know a tool
44:57Like a Knife it can kill you but if you use it like a scalpel it can cure you
45:02it’s just the way you use it the tool is the same but it’s very simple people understand it you can explain it in 30
45:09seconds if you want to try and explain rules for you know Whole Food plant-based keto it’s going to take you
45:16forever and if somebody’s 75 years old and has eaten a certain way their whole life they’re not going to understand but
45:21this is a very simple rule don’t eat between this hour and this hour whatever you want to choose it’s free you don’t
45:28have to have a lot of money because if you have disadvantaged populations
45:34they’re not going to be able to buy like you know free range organic eggs which
45:40is great but it’s expensive this is completely free it’s convenient that you’re not
45:46taking more time you’re not saying cook all your meals from scratch and raise your own chickens it’s convenient it’s
45:53not you’re going to save time because you don’t have to go buy the food you don’t have to eat the food and you don’t have to clean up so it’s just a lot more
46:00convenient for people it’s going to make your life simpler it’s flexible you don’t have to always do it you can do it
46:07sometimes and not do it other times if it’s holidays you might say I’m not fasting at all but then after the
46:13holidays I’m going to do a lot of fasting because I gained a lot of weight on my cruise and it is applies to any
46:21diet so this is important because this is not a diet diets are the foods that you eat or
46:28choose to eat fasting doesn’t tell you anything about that whether you want to be keto or you want to be plantbased or
46:35vegan or paleo or whatever you want it works with all of those diets it tells you nothing about what the foods you
46:41should eat are it only tells you that you should set aside a little bit of time to use the calories you’ve taken
46:49out whether that’s 12 hours or 16 hours or you know 20 days that’s up to you
46:54that’s completely up to you it’s always under your Choice and then the final Advantage is that it really offers
47:01unlimited power because if you have a situation where people have to lose
47:07weight for their health reasons type two diabetes or whatever and you’re not doing well with a paleo diet well you
47:13can’t get more paleo than paleo if you’re vegan you can’t get more vegan than vegan like there’s no nothing
47:18further you can do whereas with the fasting you always have a choice you can
47:23increase the duration of the fasting you can increase the frequency of the passing you can do whatever to get the
47:28results that you want because again remember you’re just allowing your body
47:34to use the calorie to use the energy that it has already stored it is
47:39literally the reason we carry body fat it’s not there for looks it’s there for you as a source of calories so if you
47:47don’t eat let your body use it if you’re getting sick because you have too much
47:52of this body fat let your body use it that’s what it was there four and that
47:58gives you sort of unparalleled options in terms of treatment of patients
48:04because now you can change so many different things not only can you change the diet but you can change the fasting
48:10time you can change the uh duration of the fasting the frequency of the fasting whatever you need to tailor it to your
48:18patients and that’s the power of intermittent fasting a tool that we’ve ignored for so long yet is literally the
48:25oldest tool in the book is the oldest dietary intervention known to humanity
48:31and it’s probably the most effective in terms of weight loss because you cannot get lower than zero so most diets
48:39restrict some foods fasting restricts every single food so as long as you’re doing it you’re understanding it this
48:46gives you a very powerful tool to treat your patients and make them better thank
Outro
48:51you
