Dr. Jason Fung – ‘Therapeutic Fasting – Solving the Two-Compartment Problem’

Dr. Jason Fung – ‘Therapeutic Fasting – Solving the Two-Compartment Problem’

so what we’re going to talk about today is really why intermittent fasting and low carbohydrate diets work whereas the calorie counters it just doesn’t seem to work right and the problem with the calorie theory is that it’s just like raw and because we don’t really understand obesity that’s why we can’t cure it right so I’m sure many of you have seen this show it’s called The Biggest Loser and it’s on North America it’s in Australia it’s everywhere right and what people do is they’re contestants that compete to lose weight and they get put on a diet it’s a calorie reduce diet and they do a lot of exercise and you’ve seen jillian michaels screaming at everybody right so it’s a lot of exercise and they don’t show it on the show but there’s actually a fairly severe caloric restriction as well it’s not a low carbohydrate diet it’s more of a kind of everything in moderation sort of an approach so the problem of course is that this show has been running for a long time and certain of the contestants have come out and said well you know this really doesn’t work now the reason more haven’t come out is because they’re essentially under a legal gag order right they’re actually not allowed to say any of this stuff but certain contestants have actually come out and so this contestant Suzanne said well they never do a reunion show why they’ve all gain that weight again and it’s not it’s not unique to the Biggest Loser a lot of diets and we’ve all done these calorie reduce diets it does the same for everything it does fine for about six months but then after that it just keeps coming back your weight plateaus then it starts to come back and everybody knows this right because everybody’s done this diet the question is why right and that’s what we really have to understand and that’s what I mean by we have to solve the two compartment problem and I’ll explain that in a second so the Biggest Loser diet despite the fact that we all know it doesn’t work is actually ranked very highly so USA News for example just this past year put the Biggest Loser diet at number three for weight loss and number 11 overall so really a very good diet and why not it’s a eat less move more sort of approach right cut your calories in increase your calories out and hey presto you’re going to lose weight so that’s why it does so well because all the doctors recommended and so on the thing is that there have been some studies that have been done on these contestants and it’s very interesting to look scientifically at what actually happens to these people as they do this sort of eat less news more approach now the Biggest Loser of course is that approach on steroids rates or eating a lot less and you’re moving a lot more and that’s why you get these dramatic weight losses so one season they actually took these contestants made them signed consents and then actually did metabolic studies on them and what’s interesting is that at first it looks amazing right and we’ve all seen that show right the before on the after it looks amazing and the studies really bear that out so if you look at the before and after if you look at the composition of weight loss so at week six and week 30 at the end of the show is week 30 you can see that they’ve lost a lot of weight right this is 60 kilograms right and this is fat mass so most of it is fat right everybody says aw you’re going to lose muscle you lose muscle another losing mostly fat there’s a little bit of muscle loss but it’s mostly fat and this is their body fat percentage you can see it’s follows a pretty steady trend downwards and the average went from 329 pounds to 202 pounds so an amazing result right body fat went from 49% to 28% so at the end of the show you get these great results you have the end of the show everybody wins and they pretend like everything’s fine but we know that it isn’t and why not what’s the problem it sounds like it should work right you keep doing what you’re doing and you’ll keep losing weight but you don’t and the reason and we’ve known this for at least a hundred years is that your metabolism starts to slow down and this is what happened to the metabolism of all these contestants and you can see in the solid bar that’s their baseline rate of metabolism before they start at this and the open circles is that afterwards you can see that in virtually every case these people are cutting the amount of calories they expend by a lot okay so you can look at some of these dramatic examples so this fellow for example list starts out by earning thirty five hundred calories a day and he’s dropped all the way to about seventeen hundred calories a day right and it’s not just him it’s everybody if you take the entire group of people the average decrease in metabolism is over seven hundred calories a day right so if you start by burning thirty five hundred which is a lot so you start at two thousand you’re going to drop down to like twelve thirteen hundred by the end of the show so you wonder why you’re not losing weight well it’s because your metabolism has slowed down so much that if you’re burning thirteen hundred and you are eating 1,500 remember that’s still a lot less than you used to eat you’re going to gain the weight back that’s exactly what we all know happens you feel cold you feel tired if you’re hungry you feel like and the weight is going back up right and that’s the problem right we all know that’s the problem it’s the decrease in metabolism so you can try to make up for it with more exercise right and that’s what they pretend that you can do so you can see that baseline there’s a certain amount which is resting metabolic rate certain amount of exercise during the show they burn a hell of a lot of calories as exercise you see that the gram tops your total energy expenditure is better but when you stop exercising for like you know five hours a day then your exercise goes down but look at what’s happened to your basal metabolism this is your resting metabolic rate it’s already gone down by week six okay so don’t kid yourself this is happening all the time but by week thirty it’s gone down even or and that’s the whole problem you get this metabolic slowdown and because you’re not burning as much energy you don’t have that you know liveliness you don’t feel very good and you can see this in this graph you can see this is the Biggest Loser contestants and you see that the basal metabolic rate just keeps on going down but there’s a similar extreme measure that doesn’t seem to have this problem and the question is why so you can look at bariatric surgery so bariatric surgery is stomach stapling surgery right so you cut your stomach into the size of a walnut you really just can’t eat and you can’t eat for months and months and months and guess what the weight goes down right that’s not a surprise the surprise is that it works to keep weight off in the long term yeah there are a lot of problems with this okay so let’s be clear I’m not recommending it for anybody right but if you look at the resting metabolic rate with a similarly sort of extreme measure it goes back up the question is why so this is another study of the long-term effects of Bariatrics and you can see that a baseline and a follow-up this is several years later the resting metabolic rate and the total energy expenditure how much energy you’re burning has really not gone down right as opposed to the eat less move more where it keeps going down keeps going down until you fail right that of course is the saddest part of all right the saddest part of the entire thing is that we know about this metabolic slowdown this was shown in 1915 so we’ve known about it for a hundred years what I think is sad is that we give people this really horrific advice to eat less and move more and then when they fail we blame them for it right and that’s basically you’re blaming the victim because here’s this poor fellow or poor lady who’s victimized because they’re suffering from obesity from type 2 diabetes you give them really bad advice which you know is going to fail because we’ve all done it it fails every single time and then when the weight goes back you say yeah you should have listened to me better you should have had more willpower you shouldn’t have eaten that bagel or whatever it is you tell people right and that’s really the saddest part of all is that we try to pretend that the advice that we give is really good and the failure lies with all of you right but doesn’t doesn’t make any sense right how can like forty fifty percent of the population be so morally bankrupt that they let this happen to them is it not more logical that the advice that we gave was just really crappy that seems to me much more sensible so we’re going to explain why this sort of discrepancy exists so in order to do that you have to understand what happens when you eat okay so what happens when you eat is that insulin goes up so most foods almost all foods have a mixture of macronutrients fat carbohydrates and protein so your insulin goes up to a varying degree and insulin basically is the hormone that tells your body to store fat so it stops your body from burning fat you start to store some of the sugar and store some of the fat okay and this is normal this is a normal situation so carbohydrates get turned into glycogen which are chains of glucose so chains of glucose in the liver is basically a storage form of sugar okay and when you have too much of that then your liver produces lipids which is called de novo lipogenesis and it basically stores fat okay so when you don’t eat when you’re fasting so fasting is merely the absence of eating your insulin levels fall and that’s a signal to start pulling some of that energy out right so you’re going to start by pulling some energy out from the glycogen which is your stored sugar and you’re going to pour some pull some energy out of the stored fat so you can think of it the glycogen like a refrigerator right you’re storing food energy and the reason it’s like a refrigerator is that it’s easy to access so you can get put food in easily you can take food out easily right it’s just food energy and the fat is more like your freezer okay so you can store more of it but it’s in your basement you know it’s hard to get to it’s hard to get out it’s hard to put in so you generally prefer to use your refrigerator and it’s the same idea you have two storage forms of energy one easy to use and one not so easy to use the refrigerator though has a limited capacity so if you put if you have too much stuff you have no choice but to put it in your freezer now the reason that the calories don’t work is that they operate on what I call a one compartment model okay so that means they pretend that all your calories goes in to your body and it’s all the same all your calories are the same they’re stored in one giant compartment like this sink and when it comes to taking out energy it all comes out of the same thing right therefore if you follow this sort of very simplistic incorrect model what you see is that if you simply reduce the calories going in you’ll reduce your weight and if you increase the calories out you’ll increase the rate but the entire premise of this sort of calories in calories out model is completely fictitious because we know that’s not what happens in the body the body doesn’t have some giant vat of calories right you can store sugar you can store fat it’s not some giant vat of calories that’s held somewhere in your liver right but that’s what they all pretend it is so if you have the entire wrong idea of why this should work then it’s not going to work what instead is a better model is a two compartment model that is there are two places in the body where you can store food you’ve got your fridge and you’ve got your freezer your calories goes in into your fridge calories goes from the fridge because that’s the easiest place it goes but there’s a third thing that you have to consider and that is how much food goes back and forth between the freezer and the fridge because that’s what we’re really interested in this the fat but that’s the one that’s much harder to get to right and the question is what’s controlling this because that’s really the key and it turns out that the main player is insulin we know this because insulin inhibits lipolysis right what that means is it stops you from getting the fat coming out that’s a job that’s a normal job so if you have a lot of insulin right so normally if you eat a huge meal your insulin is high it’s going to tell the body to move all the storage in this way if your insulin is very high then you can’t get the food back out this way and that’s the problem so if you have a lot of insulin resistance for example which keeps your insulin levels very high it’s like that freezer is kind of locked away in the basement behind the lock you know steel bar you can’t get at it so what happens now when you start reducing your calories if you start reducing your calories in and you can’t get at your storage what your body is simply going to do is reduce the calories out that’s what it does right because it’s not going to keep losing weight until you die that’s just ridiculous right so if you look at the Women’s Health Initiative which was a huge fifty thousand person study they reduce calories by 350 odd per day for like seven years and they estimated that people would lose 30 pounds women would lose 30 pounds per year right so in seven years they should have lost 210 pounds right of course that didn’t happen how much did they lose not even a single pound it was ridiculous because what happened of course is that their body is if you’re not affecting me in insulin you can’t get at that fat you’re just going to reduce your calorie though and notice here of course that we’re not breaking any laws of thermodynamics right calories in calories out yeah you’re accounting for all the calories but what’s important is the compartmentalization of energy right that’s what we’re talking about not the total energy but where it goes right because that’s what we want to know if you eat and you just burn it off who cares that’d be great but if you eat and all of it goes into fat well now you care a lot right but it’s not that calories are imbalance if you eat an extra 500 calories your body burns it all off as Fat Bob burns it all off as heat yeah who cares you don’t have any extra body fat but if you get 500 extra calories boom the insulin is telling it all to shunt into here well that’s a problem and that’s really the problem of the two compartment syndrome so if you look at what happens during fasting what happens because everybody worries about this right Oh what about protein you’re burning your muscle right so this is a study by Kevin hall from the NIH and he basically looked what happens during fasting and this is what happens right so for the first couple of days of fasting what you see is that carbohydrate oxidation goes off it goes way up right in other words you’re burning sugar you can see that fat doesn’t actually move for a couple of days you’re not burning a hell of a lot of fat right and then as you run out of the glycogen remember that the glycogen is you’re easily accessed energy but limited in terms of how much you can store once it all burns out then look fat oxidation goes off now you’re burning fat for energy that’s perfect that’s exactly what we want to do but what happened to protein are you burning muscle hell no it goes up slightly okay at the very beginning then drops so protein is not a storage form of energy why would your body burn it for energy right you hear this argument all the time you’re going to burn muscle right so it’s ridiculous right because you’re telling me that the way we’re designed is to store energy as fat but when the chips are down we’ll burn muscle right okay like I don’t think so right it’s like if you have a wood-burning stove you store firewood right because you’re going to burn it but when the chips are down you don’t you chop up your sofa and throw it into the fire right it’s crazy the other thing that’s ridiculous is that if you have repeated fast famine cycles like cavemen might have had for instance so you store fat burn burn muscle right so at the end of a few of these cycles you’re like one giant ball of 100% fat right it’s like that’s what happens to the Bears right it’s like come on don’t be ridiculous you don’t burn muscle protein yes you do need a certain amount of protein to maintain your lean protein right but it’s not increased that’s my point it’s not that it’s not zero there is some right but it’s not increased in response to fasting so the reason that I talk about fasting and low carbohydrate diets is that what it does very effectively and probably more effectively than any other intervention is it empties out that fridge right and remember what you want to do is get rid of all that insulin – right because now if you don’t have insulin telling your body to shunt all that energy into fat now you can start to move your calories out this way right if you have a lot of insulin so we do this for example if if we give people exhaustion as insulin they can’t lose weight right even if they fast it’s very hard because they can’t access that fat they just keep reducing their calorie expenditure but the whole point is that fasting provides the easiest way you get rid of all that glycogen you got your insulin down so you can actually access your body fat and there and the whole thing is that why can’t you right you know I asked my son one time a few years ago you know how do you lose weight these goes here’s six or seven at the time and he goes just don’t eat so easy right it’s like huh how can you be so right about this point that has escaped like 99% of the world’s doctors and dietitians right if you don’t need you’re going to lose weight and here’s the thing to understand there’s nothing wrong with it that’s the way we’re built right that’s the way Lions are built its we tigers are built that’s what bears are built that’s the way we’re built we’re built to withstand these repeated episodes where there’s no food right because back in the caveman days there’s no McDonald’s there’s no refrigerator there’s nothing there there are times you’re going to have nothing that’s why you have fat right that’s the whole point so one of the most ironic things is that this is what you hear all the time fasting is going to put you into starvation mode right huh this is actually very ironic because starvation mode refers to the idea that your metabolism slows to such an extent that you’re going to regain weight okay so I’ve heard that before somewhere right that’s exactly what happens when you try to reduce your calories right if you don’t do anything about your insulin and just reduce your calories your metabolism goes down you’re going into starvation mode but what happens during fasting does it happen well here’s a study of four consecutive days of fasting right so this is in normal people right and what you see is that at the top the weight goes down right so that’s great that’s exactly what we expect to see but what happens to your REE this is this middle line here that’s the resting energy expenditure right that’s your basal metabolism it doesn’t go down it goes up right you’re burning more energy than you did now you might think why is that so well it makes a lot of sense because suppose again you’re a caveman and there’s nothing to eat it’s winter there’s nothing to eat right so if your body starts shutting down then you’re even less likely to find something to eat because you’re tired you can’t go out there and hunt a woolly mammoth you’re tired right you need to sleep so that’s gonna you’re all going to die like that right your body is just not that stupid right your body says wow you have nothing to eat so I’m going to give you energy I’m going to increase the amount of energy you’re burning and I’m going to provide it from your fat stores because you need to go out and eat and fill up this refrigerator again right so that’s exactly what you do otherwise we wouldn’t be here right it’d be like cockroaches and insects running the world so what happens to your vo2 right that’s how much oxygen you can metabolize right does it slow down no it goes up right again you have more capacity to do exercise more energy and why is that so one you’re burning fat for energy and your body’s like whoo there’s a lot of this right so there’s plenty of it let’s go but the other thing you see is that the norepinephrine so norepinephrine and epinephrine are called adrenaline or noradrenaline so your body is actually providing you with a big kick in the pants to keep your energy expenditure high because that’s what you need to do to survive so insulin drops which is one of the major things that we want to see and your hormone so that’s a hormonal remember obesity is a hormonal disease it goes up it’s providing you the tools to burn fat so there’s no starvation mode actually it’s quite the opposite it goes up you can do something called alternate daily fasting which is kind of one day of fasting one-off and in these studies is not actually a full fast so they still allow about 500 calories on those fasting day so it’s not even a true fast but the calories are low that you still get the benefits and you again if you look at the resting metabolic rate which is the first line you can see that from baseline to day 22 so you know a couple of weeks of alternate daily fasting your resting metabolic rate really hasn’t dropped your fat oxidation goes way up right so you’re burning fat you can’t argue with that right you can measure these things you’re burning fat why because you have no carbohydrate to burn right because you’re clearing out that fridge you’re clearing out all that storage sugar and burning fat that’s great that’s exactly what we want do the other thing we talked a little bit about already is that you’re going to burn muscle right and again the idea is that here you’re going to burn protein to provide glucose right and this doesn’t actually happen and this has been known again for 20-25 years so if you look at your reah reah is this big line camp so it’s a breakdown product of protein so you can see that you excrete a certain amount of nitrogen every day you’re also taking in a certain amount of nitrogen every day right this is under normal conditions now you fast people like you just give them nothing to eat well what happens well there’s virtually no you’re really out right now there’s nothing going in to but what you you notice is that you’re not burning muscle because if you’re burning muscle that urea should skyrocket or at least be as high as this your body is actively conserving your protein your muscle mass right and that’s what happens during fasting and you can do 70 days of alternate daily fasting right so 70 days is more than two in a bit months and what you see is that if you measure fat mass and fat free mass in this study you can see that fat mass goes down very nicely from forty three point five to thirty eight point one kilos and the fat free mass your lean mass doesn’t move at all so these are sort of some of the myths that everybody tells you right servation mode burning protein and here’s my favorite right it doesn’t work that is never going to work right it’s like okay genius if you don’t eat do you think you will lose weight right well yes you will right so it’s not exactly a very good comeback for people to say it won’t work because it will definitely work okay it will definitely work I’m not saying it’s easy okay that’s a whole other thing can you do it that’s a separate question I actually think that most people can do it but if you are able to do it yes you will lose weight right and here’s the thing so back in the 1960s they have done a bunch of studies on these patients and what they did was they admitted them to hospital they did that back then and they just watched them and you can see that people lose weight and here’s the thing that always says people are goes oh how about women women shouldn’t fast like why not don’t you think you’ll lose weight yes you will now if you’re underweight then yeah you shouldn’t be fasting right you’re going to get a man areia you’re going to get menstrual problems but if your need to lose weight yes you will lose weight and that’s exactly what they found in all these studies so you have men they lose weight women they lose weight right and what you can see that it’s fairly steady there’s no kind of drop-off right there’s no drop off that kind of dreaded weight plateau because that’s the whole problem with weight regain is that we all plateau there’s so many advantages to fasting that are just not available in that it’s completely different from most other diets which tell you what to do because this is really the opposite it’s something you don’t do right so one of the biggest advantages is really that it’s completely simple you can explain it in like two seconds and everybody understands intrinsically what it is right now there are variations right there’s fact fasters juice fasts there’s you know water-only fast there’s no water fasts there’s all kinds of variations but at it’s very core it’s easy to understand and that’s important because if people don’t understand what you’re trying to do they can’t do it right it’s free like you know as much as I would love to always eat home-cooked meals and you know long simmered bone broth the truth is that most of us sometimes don’t have the time and don’t have the inclination don’t have the money if you want to eat grass-fed beef every day it’s going to cost you you want to eat organic all the time it’s going to cost you not saying that you shouldn’t but it’s expensive and some people just have no money so I have people who write me from the Philippines and they’re like you know I got all this stuff and I can’t afford anything it’s like well there is no cost there’s no cost at all it’s convenient right so again you can cook all you want but it takes time right it takes time and sometimes you just don’t have the time but this one there’s no shopping there’s no preparation there’s no cooking there’s no cleanup there’s no eating right there’s nothing it’s so convenient because again the key is it’s not something to do it’s something to not do right and that makes it completely different in sometimes something that you can add something that’s completely flexible right so it’s not like oh yeah you need to eat six times a day right it’s like sometimes you just don’t want to eat a snack today sometimes you’re busy right well this is going to give you more time you can put it in anywhere you can do it tomorrow and you cannot do it the whole next week and then do it again right you can do whatever you want it’s completely flexible do it for 12 hours you could do it for 12 days right it doesn’t matter and really the the point is that you can add it to any diet because again it’s something that you can put in and fit in wherever you need to right so say you want to eat the you know the rice diet or something like that you get still fast right that’s the whole point you don’t eat meat you can still fast right you don’t eat wheat you can still fast you have a nut allergy you can still fast right you don’t have time hey you can so fast you don’t have money you can still fast you’re traveling all day you can still fast right you know cook yeah you can still fast right and probably the most important thing is that it really has unlimited power right and it’s a doctor sometimes you get into these things where you want to do something and it’s not strong enough right well you can just keep fasting until you get the results you see as I said if you don’t eat you will lose weight right you’re almost it’s almost impossible to not write can you keep it up that’s a separate question right I’m not saying it’s easy I’m not saying that I mean you do have to have the proper medical supervision especially if you’re on medications so on but you could fast you could fast I have a 75 year old who did like 30 days right you felt great right the world record is 382 days you can keep going right and this is the whole point is that this gives you options because it’s not a diet it’s no diet it’s nothing right it’s like Costanza to show about nothing right there’s a talk about nothing right Georgie stands us so smart that’s the whole point is that because it’s the opposite it gives you so much flexibility and it has the ability to really free ourselves so the chains that bind us down right we have all these problems right the number one problem in the world today right you got heart attacks you got cancer you got strokes you got diabetes you got kidney disease and it’s all due to obesity it’s all due to diabetes but yet we have the ability to free ourselves from all of these modern afflictions right only with the application of a technique they new 5,000 years ago the ancient Greeks were all about fasting not for health they didn’t have a lot of obesity back then but because it gave you energy gave you like mental focus right that’s why they did it and these involuntary periods of fasting eventually got taken out right as we started getting more reliable food then religion started introducing periods of fasting right so if you look at any major religion in the world they have periods of fasting their periods of feasting – that’s balanced by periods of fasting right I remember that they’re not trying to kill all their practitioners right not like oh you should fast you’ll die haha that’s not it at all right it did it because there is something deeply intrinsically beneficial to the fasting right and it was always known always it’s a cleanse it’s a detox right there’s probably only one thing that the three most influential people in the history of the world agreed on right so the Prophet Muhammad Jesus Christ and Buddha they all agreed on one thing and that is fasting is very beneficial it’s uniquely beneficial not only for the spirit but also for your body we need to clean ourselves out of this junk that accumulates right all this extra sugar all the insulin all the fat we need to clean it out once in a while right it’s a spring cleaning that’s all it is and yet with the application of this kind of ancient time-tested technique we can break free of all this right you know in the last century we broke free of a lot of infectious diseases right tuberculosis pneumonia and all this and now all that replaced with was all these diseases but we have the knowledge we only have to apply it and that’s the most ironic part of all we won’t but there’s no reason why we won’t we’ve always been told by everybody that we have to do that and yet why do we not my son knew it any questions we have a couple of minutes left thank you very much


  • TheIgnobleSavage says:

    Is it true thouhh that if you want to gain muscle though you need a calorie surplus?

  • Scott Jones says:

    Excellent 👏

  • TheHolySC says:

    All those diet scams out there WANT you to gain back the weight after you are done so they can resell it back to you. Fasting is free.

  • Let'sArt says:

    Would Keto, fasting, or carnivore diet be best for a 5'7 169lb 27 yr old scandanavian female who's had two kids and is moderately to not very active on a daily basis? I want to try keto or carnivore and fasting, but I don't want to do something that isn't right for me.

  • Brenda Bogowith says:

    Sooo..all those anorexics who weigh 78 lbs..where did their muscle go? You will tap into muscle once your fat is gone.

  • ScienceGuy says:

    Why doesn’t this work:
    – decrease calories into the fridge (calorie restricted diet).
    – energy from eating isn’t sufficient for the day’s activities (including BMR).
    – extra energy from the freezer (fat) is required.
    – decrease fat over time.

    Restricting the calories you eat should force your body to use fat to account for the decreased energy in the ‘fridge.’

  • AVA DEA says:

    "the calorie-theory is just like… wrong" 😆 made my day!

  • mike c says:

    Your enjoyment of food will go to a new level when you do this. Since I am only eating once a day when I'm fasting I like to break my fast with something delicious. The $12 strip steak with fresh asparagus. Slow-cooked pulled pork. A nice fresh chef salad or antipasto. Chicken wings. Filet mignon. Looking forward to that all day really helps and eat as much as you want.

  • AK Henderson says:

    If you don't have health insurance.. just Subscribe!

  • Football Investors Club says:

    I am also someone who has benefited greatly from this knowledge. I went from 273 lbs to current weight of 212lbs in a little over 6 months, basically fasting 15 hours daily & removing sugar from my diet & exercising 10,000 steps daily. Drank more water, added MSM & Vitamin C to my drinking water as my only supplements.

    I take no medications and feel healthy all day, everyday. I expect to be my ideal weight in 3 months time and stay there. It is really quite easy to do. Wish I knew it when i was younger as i am 51 years old but better late than never. If you are reading the comments and haven't tried this already, I highly reccomend it.

  • andrew elliott says:

    Makes total sense to me

  • Black Lighting says:

    the truth will set you free

  • Black Lighting says:

    i could probably turn my fat into about $2000 and avoid a couple doctor visits….

  • MrA says:

    I don't really get the message hear. That the body doesn't burn its stored calories?

  • Alan Kropp says:

    Thanks doc. I'm on day 5 of a 7 day fast. I appreciate your input.

  • Benji says:

    It's been a little over 2 years since I started IF, with a bit of a bumpy ride in-between. But, I have lost a little over 75 pounds. I want to thank dr Fung from saving me from obesity and all the health complications that it causes. Best doctor.

  • Sage says:

    man i love this dude. hes just like so exasperated and tired of this false info like sigh welll.. no.

  • Mark Soni says:

    Very thankful for this video. Very insightful.

  • Katherine George says:

    I found autophagy in the bible Matthew 9:17:

    14 Then John’s disciples came and asked him, “How is it that we and the Pharisees fast but your disciples do not fast?”

    15 Jesus answered, “How can the guests of the bridegroom mourn while he is still with them. The time will come when the bridegroom will be taken from them; then they will fast.

    16 “No one sews a patch of unshrunk cloth on an old garment, for the patch will pull away from the garment, making the tear worse. 17 Neither do people pour new wine into old wineskins. If they do, the skins will burst; the wine will run out and the wineskins will be ruined. No, they pour new wine into new wineskins, and both are preserved.”

  • zafar Khan says:

    As we are aware that Muslims fast during their Holy month of Ramadan. These 30 days fasting is very beneficial and an ample proof of truthfulness of Islam. At least 30 days fasting in a whole year is good for health from medical perspective.

  • 49jubilee says:

    Not just caveman days.
    How about 175 years ago

  • jeromie89 says:

    Interesting thoughts about the RMR changes before and after weight loss. Isn't it true that the bigger a person is the higher their RMR as their body will need more calories to survive/function? So the RMR will be lower for someone after weight loss?

  • Constantia de Gier says:


  • Amy C says:

    I started fasting 18 hours with a 6 hour eating window. I like it. Tomorrow is day 10. I’m calm and happy and I feel better. That stuffed sausage feeling is going away. I take quality supplements and eat quality foods. Nothing processed or refined. I felt like poop for such a long time. It’s really sad. Time to heal. Hallelujah!

  • Kane6676 says:

    Fasting is the only way for genetically fat people to lose weight. The problem for many of us is that the body wants to be fat. Even on low calorie diet the metabolism will slow to hold the fat. Diets don’t work. Excersise does very little

  • Hally Tomasheski says:

    Oh my goodness. What sense this makes to me! Where has he been for all my life?!

  • Jerry Cummings says:

    What a charming young fellow – one who exposes the truth in a wonderful sort of way. Appreciate this presentation very much.

  • Keep Calm says:

    I m fasting 5 am to 7 pm a month in Ramadan. I feel healthy.
    After that. I fasting every Monday and Thursday per week. No more diabetes. Thanks God.

  • Madonna A Madonna A says:

    Il a toute a fait raison! Moi je suis maigre et je veux rester toujours maigre! Le jeune et la meilleur chose, et quand ont dois bouffer, c est nos fruits et legumes: j ai lu le livre du Dr. Fung et c est le meilleur livre, les medicaments sont des vrai poison, ca nous rend malade, et ses escros veulent nous rendre malade, si ont ferai tous comme le Dr. fung ont serai tous en meilleur santé, et ses companies de pharmaceutique feront faillite, c est rienc le profit qui les interesse et pas notre santé! vive la Naturopathie ! et un gros merci au Dr. fung

  • Donald Leske II says:

    I have kidney partial failure and have gout. I am told by my doctor to drink lots and lots of water, adopt a vegan keto diet and eat kale, ..plus at 310lbs I must lose 50lbs ASAP. In 10 days I am down to 293lbs. Will fasting, especially water fasting harm my kidneys?

  • Bunny Biedenharn says:

    Great to see an actual MD (and one who was good enough for Cedars-Sinai, which is a big distinction) saying these things. From one chart, it's good to see that a dedicated adherent can basically bank on losing 24 pounds of FAT per year – which amounts to three waist sizes. From the graphs, I see that even between Day One and Day Two, good things begin happening. So, am I to assume that a couple on a strict KETO/OMAD diet (only the carbs which come with nutrient-dense raw vegetables/high fat/moderate protein – with absolutely NO insulin-triggering beverages between meals) can accumulate, in increments, a similar fat loss, over a year, even though our fasts only last 23 hours?

  • R0dan says:

    Very interesting. I have been following intermittent fasting for two + years after listening to Dr. Rhonda discuss this subject. After listening to this lecture I tried my first 48 hour fast. I am at the end of the fast and the unexpected result is…I am not the least bit hungry! My take away from this is do not jump into an extended fast as you are doomed to fail. Start with intermittent fasting/ restricted eating then ease into the extended fast. Next month I will try for a 72 hour fast.

  • Dark Rainbow says:

    The Nobel Prize for 2016 went to a doctor who studied and advocated fasting. The establishment isn’t trying to hide it. People just love donuts.

    Be an individual and stop loving donuts. Then go fast.

    Alright, that’s my slogan now. “Go fast!”

    Here’s another one: “Live fast and die never!”

  • B R says:

    Is adaptive glucose sparing real? After 2 years on quality keto,IF, OMAD, HIIT, my blood sugars are 200-270. Why am I still diabetic? 61, 20+ years T2D diabetic. Lost 70# first year but none 2nd. Why? Need to lose 30 more.

  • 趙苡婷 says:


  • D.J. Martin says:

    I hear that so much..
    "If you fast you are going to lose muscle!"

  • Ada Ravon says:

    why does .contrary to your claim my blood sugar rises in fasting

  • Ujjwal Jain says:

    This was a very good talk. But I'm wondering what happens to the compounds that our body can't produce itself like essential vitamins and proteins. If we do not consume them from food, won't that affect our health?

  • Broughtolife says:

    I took myself off insulin after discovering Dr. Berg on yt. Thank God! My primary at the time was telling me it was ok to drink half a glass of orange juice in the morning. My A1C went down from 8.4 to 5.5 in 3 months, and I lost 50 lbs in 6 months. I sadly got off keto, but restarted 2 months ago and I'm down 20 so far.

  • TheEmmaLucille says:

    Dr Fung est tout simplement génial.

  • John Smith says:

    I would love for him to do this speech to a room of nutritionists and personal trainers, with the camera on them. Not that it is their fault, they have just haven't been properly educated. But it would be funny to see

  • finnmacool says:

    he is brilliant …and this information can change your life.. I urge people to listen to him.. heed his advice .. I feel so blessed to have come to know about fasting .. I was fat and sick for about 15 years … i have been fasting for the past 7 months and I'm healthier and lighter than i have ever been

  • Mahesh says:

    Can someone explain how is this any different from Atkins diet ?

  • YB E says:

    Yes it does work, keto and IF helped me shed 90 pounds! No hormonal issues. Only positive results!

  • YB E says:

    Jews don't fast for cleansing reasons we fast as a form of mourning or repentance. But I do agree that the side benefits are great.

  • Sadie Tuescher says:

    How can you go low carb as a vegetarian? (I don't like meat, in fact, I hate it).

  • Nicole S says:

    I have been fasting and love it, but what seperates regular fasting from eating disorders like anorexia? I ask because I have friends who suffer from it. One has almost died several times

  • Dietitian Ny Fahaverezan' Ny Vesatra says:

    your voice is so relaxing i think it is perfect

  • sue thomas says:


  • Chrystal Powell says:

    This is so informative.

  • Devorah BatMiriamGoldaVMordecai Bayer says:

    Many of us who are compliant post bariatric rn y did not haveany benefits and are now meeting with success on Keto.

  • Lakshya Choithani says:

    Hi sir once we loose weight how We r supposed to maintain

  • Shenandoah says:

    I'm on day 2 of a 7 day fast. I've been on keto for about 5 months, but still struggling because I still crave sugar and have given into the urge to binge on ice cream too many times. My binges are much less frequent, but still too often. I'm trying to reset my system and after my fast plan to do strict keto with no keto treats, no alternative sweeteners, not even berries. I still have about 80 pounds to lose.

  • mike Jones says:

    His teaching is from past teaching but its helpful because we never know about this way of healing. So it's TRUE everything repeats itself

  • Night Knight says:

    From one physician to another, Dr. Jason Fung knows what he's talking about, (even though he cheated off of me during medical school examinations…joking of course). I've not changed anything about what I eat, simply when I eat. Started intermittent fasting 6 days per week on a 18hr fast / 6hr fed window and have lost 70lbs in 4months. Now my wife thinks I look too much like a ripped body builder. The food and pharm industries don't want us doing this because there's no money for them in it. It works with a bit of discipline and self restraint, the 6hr eating window removes nearly all snacks from your life. It works great and costs absolutely nothing…yup even doctors like to save money and time!

  • James Broffardski says:

    "THAT would just be RETARDED" – jason fung, m.d.

  • Leo Joseph says:

    Thank You Dr Fung for this video. I started fasting daily for 12-15 hours this month and it has helped me lose a few more pounds. Which fasting period is the most optimum or effective?

  • Andras Libal says:

    The problem with the calorie theory is just that it's … WRONG :))))

  • Gerald Manley says:

    Just like bears

  • A A says:

    On my 4th day on a water fast, never felt better and that's coming from a glutton

  • accitenor says:

    I bought his book, 'The Diabetes Code' two weeks ago and started fasting 17 hours a day (I eat from 10am to 5pm). My blood sugar has dropped 20 to 30 points both before and after meals!

  • Mr.Sojek says:

    Forgive my ignorance but still don't get it. If caloric deficit slows down metabolism so should fasting do that even more. When in caloric deficit body should burn all calories intake and if there's more energy needed, then glycogen should allow stored fat to become more accessible.
    If insulin stops body from getting fat surplus then 3000kcal daily should be less beneficial than 1500kcal. It is also impossible to provide the right amount of calories, there will always be deficit or surplus.
    If someone’s diet is OMAD 2500kcal in one fat-based meal would that still be beneficial?

  • DEBJIT DAS says:


  • Andrea Ingram says:

    Fasting benefits for spirit building body and soul. Alternate day fasting. Why Therapeutic Fasting Works Myths debunked with charts on video. A fast day is around 500 calories.

  • Edward Smith says:

    Fasting is like quitting smoking. You can't do it moderately. One cigarette will take you back to day one. Get past day three and the cravings negligible with both fasting and quitting smoking. Same thing with fasting. None of it is hard. You have to make your mind up to do it and not even think…..I can,t do it, I love food too much. Just do it!

  • JON Cunningham says:

    Fasting for Health, not for weight loss is where the focus should be.
    When we stop cramming things down our throats 6 times a day our system can rest, recuperate and rejuvenate. Whether it is water, urine, or juice fasting it is all good, & to eat less. Lots of liquid is needed for any cleansing fast to work well. I like using distilled water to fast to get all bad stuff out. All this food stuffing is making all of us very ill. The body needs a break now and then from the constant receiving of junk whether it is good or bad junk . This prevents the body from breaking down and we die of sicknesses. Its even in the Bible for healing. Fullness of bread was the main problem, not even what they ate. IMO

  • Lawrence Ross says:

    Dr Fung, if fasting causes a condition of autophagy, doesn’t it follow that your kidney function would show an elevated bun/creatatine/gfr? Thank you. Have been very successful in improving my insulin resistance by keto, fasting and cutting out ALL alcohol !

  • Mark Freeman says:

    The one thing that religions agree on is fasting!

  • Sifu Slim says:

    Great info. Cease the use incessant use of "right?"
    In Aloha,
    Sifu Slim
    Author of Sedentary Nation
    The other part that is lesser mentioned is that proper exercise does so many things to our emotions and physiology. Lowering stress and improving digestion and sleep are incredibly important in health.

    Part of good health is losing excess weight and toxicity–especially toxic and detrimental molecules stored in fat.

  • gtcstorm40 says:

    If we never ate junk food in the first place then fasting would not be necessary. The blue zones eat tons of carbs and they are mean and lean. This strategy is a band aid imo. It does "work" but I think there is a better way.

  • American Mythology says:

    I’ve been intermittent fasting and my parents are so worried! Lol

  • EX MIUWU103 says:

    Any questions, I got 2 seconds left.

  • i. zak says:

    I call him Doctor "right?"

  • Pablo Horteg says:

    This works. The 18:6 rule is the easiest way imo. Don't eat breakfast, eat lunch at 12pm and have dinner before 6pm. Eliminates unhealthy snacking and is easy to do (you are fasting as you sleep). You will lose weight (unless you absolutely gorge yourself with McDonalds during the feed window). Other advantages also — save time, save money, concentration boost, willpower boost.

  • JMichael Taylor says:

    Wow! I started doing alternate day fasting in 1999. Was just an idea I came up with. Made sense to me. I have a nice medical background, so, why not use it?! I was told it wouldn't work, it was too radical, my Veterans Administration doctors told me it was unnecessary, and loved ones thought I was a bit off. Well, it was working!
    Now, this doctor comes along 20 years later and verifies what I had previously done.
    This does work, folks. It requires discipline on your fasting days, but don't give up. It gets easier as you do it more often.
    Good luck, good health, and I hope you are successful!

  • Fred Cory says:

    If it wasn't for Gary Taubes, Dr. Fung would still be a conventional nephrologist merely managing the ravages of diabetes.

  • Library Files says:

    This is good if everything is working normal. However, I think that it’s more complex than this. I think their are many pathways to diabetes. My blood sugars go into the hundreds yet, when I exercise, my sugars drop into the 40s if I push hard enough. I produce insulin but why do I get hypoglycemic and my energy drop to the point where I become ataxic?

  • P MB says:

    "..just like the Lions, Tigers, and Bears… we are built that way" ; I enjoyed his discussion,… enlightening.

  • Mr man says:

    its fake,,,i fast for 1 year and i now weigh only 2.4 kg

  • ouivalerie says:

    The entire population was skinny back in 60s, 70s….all the years past…..skinnier as it went….there were occasional fat people that didn't get like 400 lbs, super fat was like 200 lbs…..something happened…probably cows milk and cheese and the hormones….it's irreversible…..we can find ways to tweak our selves….thyroid medicine used keep anyone skinny….when it was a good brand..I hear doesn't exist now……..Money got so hard to get with sharks taking all….people were like not motivated to move without knowing they were paid…..it's motivation too…..Motivation was so strong before we didn't think about eating between meals…..3 meals kept people skinny enough….it might be too much….but the livers and intestines of the population seem to me to have all the clog….from the junk for sale and junk in vitamins and medicines and fake things in pills and junk in pills.

  • Graham Itzstein says:

    Well, I've been needing something to get me motivated to lose weight, and this has done it for me. What an interesting guy, and what an informative video. I was a bit worried that, as an insulin dependent type 2 diabetic, that the fasting might make it harder to maintain a steady level of my BSL readings. I figure if i do regular monitoring to see what effect fasting is having on my BSL's, it shouldn't be a problem to adjust accordingly.
    Thank you Dr. Fung.

  • Mike Kelley says:

    Yeah, after four days of fasting I'd kill a few people and then I'd lose weight on the jail diet. So — good?

  • Scott Bryant says:

    Great video he so right I been use with my health and my clients.

  • Christopher Barclay says:

    I think we need to go "Cave" as in caveman. Caveman did not always eat on a regular basis. He walked a great deal and probably ate mostly meat. No wheat, no sugar, no rice, etc. They did not exist back then.

  • Stephen Berson says:

    After reading Jason Fung's description of how the body utilizes stored fat and sugar when fasting I was surprised to read further where he states fasting 'POSSIBLY" CAN REVERSE HIGH BLOOD SUGAR. I would think based on his statement the body definitely would lower the blood sugar when fasting but I guess he isnt confident or sure. That makes me skeptical of the benefit of fasting in addressing type two diabetes.

  • Xymo Nau says:

    People in concentration camps were on reduced calories and every one lost weight, so what this man is saying is nonsense.

  • Dez Nicole says:

    I cant seem to get past a 50 hours fast, mentally I feel drained, tired, lethargic.. But I am healthy, I dont have diabetes or any other kinds of health issues. How long does it take till the body starts burning the fat off the body and producing energy and focus??? How much water should I be drinking while fasting? Can I go one day dry (no water) next day some water?

  • Neal Catapano says:

    Here I am, August 2019, just started this week. Ridiculously overweight, blood pressure and diabetes problems. Will report back with how I do.

  • cbell3408 says:

    Excellent information 👍👍😊

  • Kathy Noggles says:

    How often do you recommend a person do a true fast and how many hours?

  • First Last says:

    ‘Breakfast is the most important meal of the day’

  • Prashanth K S says:

    You spoke so much about low calories diets that didn't work as it reduced metabolism.

    Then you started saying fasting works.
    Isn't fasting but extreme low calories diet? Are you stressing on the days that you eat to maintain metabolism?

    Then you show benefits of fasting but say is not complete fast and they still are eating 500 kcals. Is that not similar to low calorie diet?

    And then you say people fasted for 380 days? Is that starvation fast? Is that low calorie fast?

    What you are saying is so vague and confusing. I've read a lot about IF and Keto and even practiced it. But you seem to be saying the same thing and talking about it in two different voices and perspectives. Help me make sense of what you spoke here?

    My point is, you never clearly differentiated fasting vs low cal vs starving and why each works or doesn't work.

  • Nathan Taylor says:

    Doctors v Doctors. Weight specialist v weight specialist So much information; who do you believe ? Well Dr. Fung receiving a Nobel Prize Award just might be the one to listen to….My partner and I bought both books and been doing the intermittent fasting with a little excercise for about two months now and our physical and mental status are very healthy. Fat loss is around 13lbs and there is literally no mental swings anymore our mental health is very relaxed…my fat loss goal was 20lbs but I'm thinking going to 30lbs puting me at 175lbs at 5"9…another thing is the constant sluggish feeling is completely gone.

  • Justareader says:

    Prolonged fasting rocks!
    Furthermore, a whole food plant-based diet is the only thing EVER proven to reverse and cure cardiovascular disease PERIOD!

  • TheQueenLioness100 says:

    Can you drink kumbocha while fasting?

  • KHRN2014 says:

    I can listen to him talk all day. Yes, the content, but his voice and accent!

  • Deborah Barnes says:

    I like what he is saying but wish he would just get to the point. Repeating too much.

  • 57ashdot says:

    IF is a fantastic tool for anybody who is fitness minded. Short, controlled fasts that let you hit ketosis for ~6hrs a day.

  • David Westfall says:

    I've lost almost 50 lbs since February with intermittent fasting and light strength training 3x a week. I feel way better in general (including after I eat), I have more energy, and a better ability to concentrate. I highly recommend this guy's advice.

  • C Haz says:

    Well…… with a reduced metabolism you can't eat as much, but the candle is burning lower and your life should be longer due to that, as long as you don't let the weight go back up.

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