Dr. Jason Fung: Fasting as a Therapeutic Option for Weight Loss

so what I'm gonna talk about today is intermittent fasting but before I get to that I thought I loved dr. Davis's message about undoctored and unfortunately my journey was much like his I went through medical school and then residency at UCLA and then I went and did knee disease and did it for a lot of years like 10 years or so and then realized that it really wasn't helping a lot of people like the conventional medications so so I deal with kidney disease the big the biggest cause of that is type 2 diabetes and so we would spend so much money on dialysis and drugs and drugs and drugs and it became obvious that I'm just sort of holding their hand until they get their heart attack until they get dialysis until they go blind until we chop their feet off and it's really sad to understand that the profession that you chosen is actually not really helping people and at the same time we actually understand how to help people because these are all nutritional diseases if people would lose weight the diabetes would go away if you don't get that BT's type-2 diabetes then you don't get diabetic kidney disease well that's pretty obvious but there's no money in it so nobody was promoting this stuff and it's sad because you're in the business to help people and being a doctor unfortunately you get trained in the system where you really just get taught what drugs to get and what procedures to do and what surgery to give so we went from the person that you went to to keep you healthy to the person who tells you what drug to give even if that's not the cause and it's sort of a sad state of affairs and that's what you know that's what led me to start talking and blogging and writing books and so on about these sort of things and why we use things like intermittent fasting which nobody makes money on and it sort of reminds me of a conversation I had with a friend of mine so we're in our 20s and this guy is like the smartest guy I know he worked at Google and then you know he quit after two years and retired at 40 right so really really really smart guy and he says to me one time and I said hmm you know how when you're kids you think that adults you know they have their shit together right and then you grow up and you realize nobody has their shit together and it's like yeah that's true and it's the same thing with being a doctor like you think that your doctor knows what the hell is going on and then as a doctor you realize they have no bloody idea what they're doing out here and that's the whole problem and that's why you almost have to take you know matters into your own hands you have to take your health into your own hands because you're not gonna hear it from the media you're not gonna hear it from the doctors and sometimes you gotta you got to do that cuz this is just like dr. Davis I get I get emails from people they say oh thanks for writing the book I listen to you I you know lost thirty pounds I got myself off of insulin my a1c is now normal so therefore by definition you're not diabetic and I think okay that's great and then I always think to myself which I don't say to them I always think to myself why did you have to do that despite your doctor not because of your doctor but despite your doctor and that's a very very very sad you know statement on the affair of things I had a patient once who I saw in the IDM clinic they are doing great they lost weight they they were on insulin for 20 years and I got him off in like four months is ridiculous and their a1c was normal so again non diabetic and she was like oh I'm so happy she went to her endocrinologist who's a diabetes specialist and he says oh good job and then he/she told him he was fasting and he screamed at her right it's like oh my god like any fool can see that this lady was so much healthier and yet you go to your specialist and they tell you now you should stop what you're doing which is making you healthier and everybody can see that and go back to your diet that's gonna make you sick and diabetic which is gonna lead to your amputation and your kidney disease it's like you know sometimes medicine is just such a such a logic free zone it's like ridiculous so what we're gonna talk about is another of these things that has been used it's an intervention intermittent fasting that has been used for thousands of years and recently it's gotten more popular but when I started to use it about five years ago it was considered quackery right so it was really thought to be so dangerous that you know the people had to warn them against listening to me because obviously we know that you know you have to put muffins in your mouth every three hours to survive so that's the real problem of things so this is what we're gonna talk about sorry this is the oh sorry this is not okay so I'm going to talk about intermittent fasting and kind of a little bit of how we got here so it's about obesity and this is sort of where things came from right and you you all know this so in 1977 when they came out with the Dietary Guidelines for Americans I don't think they were trying to kill people but they were trying to do the best that they could but the problem is that they you know they said oh you should eat lots of carbs which is okay if you're an op na when eating like 90% sweet potato but if you're eating all refined grains then maybe it's not the best thing and you should decrease your fat and this is the real problem this is the original food pyramid from the 1980s and you can see that bread pasta and rice are like the face of that food pyramid so every single day you're supposed to eat like six or seven slices of bread and we this was 1980 and we all thought hey this is fantastic so we all did it because we're trying to be healthy and the government was telling us that this is what we should do nobody really thinks that white bread is all that slimming so that's the problem but that wasn't their point the point was actually to try and combat heart disease which of course was probably the exact wrong thing to do but that's what we thought at the time so everybody likes to blame the people that is oh yeah we gave him great advice but they didn't listen but really they did listen so if you look at consumption of butter you know way down eggs animal protein and we ate grains and sugar sugar that was actually not supposed to they didn't recommend it but they in the sort of hysteria of anti fat they're like yeah sugar is not so bad so jelly beans and stuff were you know they're fat-free right so they it's 100% fat-free so this is the whole problem and you know we always try to blame people we say well you know the obesity crisis is because people didn't listen to us it's like they did listen to us the advice was not good but people can't admit that and that's the problem so sugar was a particular problem because you can see that the you can see that the when the dietary guidelines came out this sort of like sugar was not so bad for you so they they they increase their consumption of sugar and so you can also see that grains increase the consumption as well so it had been dropping until the 1970s and then really started to take off and if you ever if you if you live through that period of the 1980s 1990s when there's this real hysteria about five you understand you know big plates of past that oh great that's fantastic right and they we learned that in school oh yeah you should cut your fat cut out the butter cut out the cream sauce but have a big plate of pasta so this was something that we are taught but the other thing that we don't often talk about is that we're also eating a lot more frequently and I think it was sort of inadvertent because what happens is if you eat a lot of refined grains and a lot of people understand you eat a couple of slices of bread well a couple hours later you're actually really really hungry so then you want to go eat a muffin at ten thirty so we went from eating three times a day so if you look at 1977 you can see that this is the an hain survey so it's a big large nutritional survey in the marrow 1977 you can see most people are eating three meals a day so again if you live through the 1980s as you grow up you to eat breakfast lunch and dinner nobody was eating snacks nobody who's eating bedtime snacks nobody was chasing the kids around between the halves of soccer giving him juice and cookies that was what we did if you were hungry after school you'd ask your mom for a snack you'd say no you're gonna ruin your dinner and that was that if you're hungry after dinner he said you she said you should ate more that dinner and that was it right there is no snacks and that was the whole point so you went from eating three times a day to eating six times a day right so if you look at my son's schedule and I don't have that much control over it is because it's breakfast in that school you get a snack and then at lunch and then after school you go to program you get a snack and you have dinner and then you know between soccer somebody gives them a snack six times a day it's like that's before you know it and we teach these kids we ingrained this indoctrinate these kids into thinking that you must eat all the time so it doesn't feel so wrong because everybody's doing it and my teacher told me and you think they have to shit together right so it's like yeah that must be correct so then you go to the modern eating pattern and this is data from a couple years ago so they gave people a smartphone app and then they said you know check every time you eat and the the dot is when they eat and if you look at where it is you can see that people start eating in the morning and they really just don't stop until like 11 p.m. and this is the whole problem of the modern eating pattern is that we're eating very very often so you can see that we're in 1977 everybody's eating three times a day the lowest 10% of people are eating three times a day the highest 10% of people are eating 11 times a day and that's not because people didn't listen to us it's because we tell them you should eat six times a day should eat small frequent meals all the time but we never did that before no Society in human history has ever done that before because we have work to do we're not like oh yeah you know going out in the field and it's like yeah I could really use a little cookie right there's no reason to do that because it's very very difficult but that's what it is now because when we make these convenience foods which are highly processed and usually with a lot of grains and sugars so that we can eat this frequently and then we tell them they should and we're eating later so most of the calories are consumed before noon and you can see that you know we're eating all the time as well so the median daily eating duration is 14 hours and 45 minutes that's the average right that's the median I should say of everybody so if you started eating at 8 a.m. you wouldn't stop until 10:45 p.m. that's the 50th percentile right slot people are eating more than that they're starting at 7 a.m. and not in stalking until 11 p.m. so the only time we're not eating is when we're sleeping and that's one of the big problems because you know that every time you eat your insulin is going to go up assuming you're eating a mixed meal and the insulin is actually a hormone that tells your body to store food energy right I mean the whole problem of ecity is not really all that difficult if insulin goes up your body is supposed to store that food energy when you don't eat when you fast then your body is supposed to take that food energy back out and burn it and that's the reason that you don't die in your sleep every single night it's because you store it and then use it right and this is the problem if you eat instant goes up you store it if insulin goes down you burn it but you can only do one or the other if you spend all your time eating then you're gonna spend all your time putting food in it's like a one-way valve the food is going in it never comes back out so what's gonna happen over time you're going to gain weight so that's not really so difficult in fact the the English language itself provides the clue because it says you should eat breakfast break fast that's the meal that breaks your fast so you have to fast healthy living is balanced right so you have to balance the which is the Fed state and you know digestion or the fasted state if you spent eat three meals a day over 12 hours you have 12 hours of feeding 12 hours of fasting good 12 hours a day you're putting food in 12 hours a day you're taking food out now you're putting food in sort of 13 15 16 hours of the day and not taking it out because even after a meal it takes a few hours before your insulin goes back down so you know and on the other side of course as soon as you eat your insulin goes up right away so it's a there's a bit of an imbalance so you're spending not just 1415 hours with your insulin high because it takes 3 or 4 hours for your insulin to come back down to get into the fasted State you're really talking 17 18 19 hours in the fed state and now instead of 12 and 12 you're talking about sort of 18 and 6 or something like that so you're eating all the time you're putting food energy in all the time and what was the problem the problem was that now we have this big obesity crisis but there's two main issues other than the carbohydrates that and the sugar that we were told to eat it's also the frequency we're eating just too frequently so the whole problem of weight loss it is very clear so the Biggest Loser is just in a show where people compete to lose weight and they never do a reunion show because they all gain their weight back and this is the problem everybody knows it so anybody who's tried to lose weight knows that it's really really hard to get that off and this sort of calorie restriction diet which has cut a few calories off of each meal 500 calories a day but eat six times a day that sort of advice is the sort of standard advice so if you look at the Biggest Loser diet for example you reduce your calories your increase your exercise and it ranks really well in these sort of rankings of diets number three for weight loss ketogenic diets on the other hand were dead last so that's what people think this is what the the sort of nutritional authorities think about weight loss this is what you should do and we pretend we're living in this era of evidence-based medicine that is okay if you think it works well show me the study to show that it works well we've done those studies so this is the today's study for example published in the New England Journal Medicine which is actually the probably the most prestigious medical journal in the world and what they did is they took this approach which is calorie deficit approach which is decreasing energy intake you know cutting doubt the fat cutting out the sugar the sugar probably a good thing and then they compared sort of lifestyle everybody got metformin which is a diabetic drug because these were type 2 diabetics everybody got metformin and then you either got rosy glitter zone which actually caused a bit of weight gain on the right and on the red but then you also have this the the lifestyle versus no lifestyle treatment so cutting your calories increasing your energy because this is what they're trying to do you can see that this green line they started out a body mass index of 34 and after you know five years of hard work he ended with a body mass index of 34 so it didn't really work at all he only got back to baseline through a lot of hard work at the fifth year if before that you're actually gaining weight so this is this is the approach it doesn't work and this is the diabetes prevention program which is the same thing so if you look at lifestyle which is the the circle you can see that in the first six months you do really great you lose a lot of weight six seven kilograms 15 pounds but by the end of that four or five years again your weight loss is no different thing if you did nothing at all so if you got no dietary advice you didn't cut your calories it didn't make any difference right so there's the evidence though so we have this intervention and cutting calories little few calories every day it doesn't really work this is the Women's Health Initiative which is a huge randomized control trial almost 50,000 women again here it is these women are cutting almost 360 calories every single day and they're doing it year after year and they increase our exercise so this is metabolic equivalency went from ten to eleven point one about a 10% increase in their physical activity they're moving more they're walking more and all that well what happened well here's the difference overall at the end of seven eight nine years there's barely any difference at all if you measure waist circumference and so on you might think oh well they're actually gaining more muscle it turns out they're not there's actually no difference at all so here we have three randomized control trials of this calorie restricted diet and it doesn't work we've proved it and yet if you go to talk to your doctor he'll say well what you need to do is just cut your calories and exercise more calories in calories out there you go it's like but it's not true you know it doesn't work we've proved it doesn't work and the hardest part - for people to understand is this is when people stay on their diet because this is this is a study so you measure the people who stay on their diet these people are not failing because they fail to follow the diet they're failing because the diet doesn't work and this is what's really important because we tend to ascribe a lot of blame on to the victims we play this game called blame-the-victim which is that as we gave you this advice to lose weight you didn't lose weight because you didn't follow the advice so we're blaming them but they're the ones who are suffering they're the ones we're getting sick they're the ones taking the diabetes and that's like the most unfair thing we do because the evidence shows that this approach actually just doesn't work and we know this doesn't work really if you look at the UK general practice database what you can do is look at people who have tried to lose weight using this sort of advice and the probability of achieving a normal weight if you're morbidly obese is 0.1% in other words this diet that we recommend as doctors is has a 99.9 percent failure rate but when you fail we're gonna blame you hundred percent of the time like that's that's the reality of modern medicine everybody knows this everybody says this so you take these sort of bible of diabetes say Jocelyn's diabetes it says well you know restriction of calories is the cornerstone yet none of these approaches has any proven merit so as in we know it doesn't work but we're gonna recommend it right hand becau obesity dietary therapy reduction of energy results of such diets are known to be poor and not long-lasting so we know it doesn't work but we're gonna recommend it anyway and you know that's so illogical like seriously seriously bad so we actually know why it doesn't work because we've studied this over a hundred years we know why this sort of cut 500 calories a day every single day just doesn't work because of slowing metabolism that is there's two main problems one is the slowing metabolism if you cut somebody's calories down their daily energy expenditure is also going to go down so this study from nineteen seventeen so as in a hundred years ago we knew this if you cut their calorie its intake by about thirty percent what they see is a 30% reduction in basal metabolism you see it in Ancel keys --is biology of human starvation which was actually not a starvation study it was a fifteen hundred calorie a day diet so not very different than anything that we recommend now so we think people take say 2,000 calories you should cut it to 1500 that's what this study is so when you cut their calories by about 40% guess what their metabolic rate drops by about 40% their heart volume shrank by 20% the heart rate slowed the body temperature goes down because it's it takes a lot of energy to to burn to burn those calories to generate body heat so if your your body doesn't want to burn so much because it's not getting in so much and we've proven this and in the in the lab - so Rudy Leibel he did this fantastic experiment where he took people and he he gave them their at their initial weight he made them gain weight by force-feeding them they had us you know this milkshake that they had to take so they gain 10% weight then they went to back to their initial weight then they went to 10% weight loss and at all points they measured their basal metabolic rate so you see that 10% body weight gain your body actually ramps up its metabolism it's burning about 500 calories per day more it's trying to burn it off right as you go back to your initial weight it goes back to his baseline and as you lose weight you're burning about 300 calories a day less so you can't just say oh I'm gonna cut you know this is the big fallacy of these calories and calories out people because if you simply cut your calories by eating less your body will respond by earning less and then you're gonna plateau and then you're gonna regain that weight and then somebody you're gonna face that sort of massive wall of condensation of oh you let yourself go it doesn't work like come on we've already proven that and you hope that this this sort of thing goes away after a while but it never does so if you overfeed people the TE which is total energy expenditure goes up if you under feed people the total expenditure goes down and it persists over time and persists over a year so getting back to the Biggest Loser this is really what happens here is that if you measure these contestants and say when you know 6 weeks and 30 weeks what you find is that they've lost a lot of weight so it's great so they've lost they went from 329 pounds to 202 pounds body fat went from 49 percent to 28 percent over six weeks so you see the results on the TV they look fantastic so that's great but what happened to their metabolism and this is what happens you see before they started they were the dark circle after they at 30 weeks so 6 months roughly they that's the open circle and what you can see is that everybody's basal metabolism the amount of calories are burning every day and this is not exercise this is to keep your brain working to keep your liver working to keep your lungs working it's going way down so this poor guy over here for example starts off at 3500 calories and he went all the way down to here which is like 1800 calories a day so almost 1,700 calories per day he's burning less than he did before and you wonder why his calorie restricted diet is stopping working because your metabolic rates going way way way down so this is what you see in the Biggest Loser so if you look at the the shaded area that's the that's your basal metabolism that's not including exercise the white bar on top is the exercise so what you do is in the show of course they try and make up for it with insane amounts of exercise so you can boost that up but then as you go your your basal metabolic rate is still going down and this is the problem right so they got off the show they're not doing eight hours a day of whatever it is they're doing and that white bar is goes back to sort of normal and then that's it they're not burning the calories so even after they reduce their calories their weight goes back up so you see this when when you look at the Biggest Loser except for this guy who had the stomach surgery their basal metabolic their their weight goes all back off you know some people of 50 pounds more than they did at the beginning and then but it's because their basal metabolic rate is slowing so much and this is the whole problem is that we assume that energy out stays stable right so it's a two compartment problem that's the whole thing so if you have a a factorize for example you know energy producing coal burning factory you have energy in which is the coal and then when it goes in your body actually has two ways to use it you can either burn it for energy or you can store it as fat right so the energy comes in and say the coal comes in you can either burn it or you can store it when you eat calories you have the same option you can burn it or you can store it as body fat right so if you reduce the amount of energy in so say you reduce the amount of coal that comes in what we hope is that you keep burning the same amount of energy and then the fat stores will come down right that would be fantastic so if you're the manager of a coal burning factory for example you know you get a little less call you still burn the same and then you just decrease the amount of stores well that would be good except that's not what happens what actually happens is that the fat stores stay the same your energy goes down your energy out goes data down and that's the problem so the whole fallacy of calories and calories out is that that stays stable but it doesn't you've known that for a hundred years we have all the studies to prove that it doesn't work and the problem is not what you're putting in the problem is this control right here this is the main problem not this so everybody points to this but you actually have to control this because if this comes in and it goes out as energy it's okay if this comes in and goes over to fat stores then you're not okay so you're really talking about the hormonal control of energy partitioning that's the whole problem how do you control it how do you control those hormones the second big problem is hunger so what we see is that if you lose weight then you get more hungry so this is again published in the New England Journal of Medicine they took people they lost weight and then they measured something called ghrelin which is the hunger hormone and that's here so black is baseline and then we 10-week 62 what you find is that as you lose weight so you lose weight but the weight slowly comes back on but at all points again you can see that the growlin level is higher in other words you stay hungry with weight loss so you see this in terms of it will translate the ghrelin which is the hormonal mediator is going to translate into higher levels of hunger so this is the big problem so you know that if you lose weight and you don't control those sort of things then you're going to not be able to control the hunger and you're gonna eat and again this is not just a lack of willpower this is real physiology here it's like if we did that to any one of you you would be hungrier and you would eat because that's the physiology but we don't do that right we blame people and we say oh yeah you know you couldn't stop yourself from eating it's like yeah because they're ghrelin is higher you never controlled the hormonal mediators and that's the real issue of the body set weight which is that the adaptation to weight loss is to reduce your energy expenditure and increase your hunger what I'm gonna do is we're just gonna move past this a little bit so one of the problems is this right so you have to actually control insulin which is going to be the hormonal mediator of what's going to where this energy is going to go if you don't control it then you're gonna lose so if you cut 500 calories per day by cutting the fat off your meat for example that dietary fat has almost no insulin effect it has 500 calories but no insulin effect your insulin is just as high so if insulin is high you're gonna direct all that energy towards your fat stores and this is that's where you're gonna lose so how does fasting help this problem well if you look at the metabolic change as a fasting what you see is that the basal metabolic rate is maintained so this is four days of fasting what you can see is that the top is the weight the way it is steadily coming down but re E is the resting energy equivalent and what you see is that at the end of four days of not eating your major basal metabolic rate is actually 10% higher than when you started and the vo2 which is a measure of how much you know energy or burning is the same and it's because there are other hormonal changes that is as insulin goes down other hormones go up so insulin is coming down but then your counter regulatory hormones goes up including something called noradrenaline or norepinephrine as well as your sympathetic tone and growth hormone those are the counter regulatory hormones and they go up and that's how you maintain your basal metabolic break after 22 days of alternate daily fasting for example what you see is that the RMR which is your resting metabolic rate goes from 66 70 63 to 6300 which is not significantly different this study compared CR which is calorie restriction to to alternate daily fasting again you look at the adjusted resting metabolic rate the box on the right shows you that the caloric restriction reduces your energy output by 76 calories a day the fasting group only went down by 29 which were the p-values point 4 which means that's not statistically significant so again this is one of the big problems of weight loss long-term weight loss is this metabolic rate and because the fasting improves the hormonal changes about the energy partitioning it's not actually it's not actually giving you the same problems because your body is not just ratcheting down its energy expenditure what it's done is it's switched over its fuel sources from food to body fat because that's what body fat is for it's for you to use when you have nothing to eat it's not there for looks it's for you to use so use it that's all you need to do don't do something silly like eat six times a day cut your fat and cut a few calories the other problem is hunger and this is this is again ghrelin we're looking at fasting and ghrelin so they took people they fasted for 24 hours and then they measured their ghrelin at all time points and this is one of the things I always hear that if you don't eat that muffin you're gonna be so hungry you know you're gonna stuff your face afterwards so what actually happens when you don't eat for 24 hours so those are those things on top that's breakfast lunch and dinner you see that girl Ellen does spike so you do get hungry at that time but what happens when you don't eat lunch so say you skip lunch this is the first one al does go Ellen just keep going up and up and up no in fact when you get to 4 o'clock joerger Ellen has gone back down to baseline because this this line is here's baseline that is you're about as hungry eating lunch as not eating lunch and the same thing happens at dinner time joerger Ellen goes off yes then you don't eat in several hours it just goes right back down to baseline so the hunger doesn't build and build and build she comes as a wave if you ride out that wave they'll just go back to baseline and we've all done this right so you've been so busy you work right through lunch I mean did this tons of times in medical school you're too busy you didn't eat dinner yeah at 12 o'clock you're hungry at 1 o'clock you're hungry at 4 o'clock it's as if nothing happened it's as if you ate lunch and you just kept working and we know this happens because we've all done this before and we know that it's just yeah you might eat a little bit more at dinner but you're not like gravan ously starving and it's okay to not eat because what's happened is that your body has taken that food energy from your body fat and that's perfect that's exactly what we wanted to do the interesting part is when you go into the multiple-day fast what you see is that over you know four or five days the gallon goes up and down but over the ensuing days it actually goes lower and lower and lower and we see this with the with the people who are doing sort of four or five days of fasting at a time that the hunger actually starts to disappear because you're fueling your body through your body fat so then you don't have that hunger anymore and you're getting more efficient at using it so therefore it's a great strategy some people say oh wow women it doesn't help it turns out if you look at growlin women have a much bigger spike in growlin than men and so if you look at food cravings and so on women tend to feel it more so they actually get more benefit because some people say oh women should never fast it's like why they got more benefit from that than anybody else and the weight loss is the same if you look at food cravings for example you can compare a low calorie diet to a very low calorie diet so it's interesting because you can take any of these cravings sweets or high fat whatever you put them on a twelve thirteen hundred calorie a day diet those cravings don't do anything so this is the measure of the cravings and this is how much they have cravings the low calorie diet does nothing but if you eat practically nothing at all the cravings just disappear because the cravings are like an itch so any parent knows that if your child is really itchy the last thing you really want to do this Pratchett because it's gonna get more itchy and cravings are the same so by going into these instrument fasting where you're really allowing nothing at all that's gonna make more benefit for your cravings than the other and controlling hunger is the big issue it's not about controlling calories I mean that's like grade school stuff right you have to control the metabolic rate and you have to control your hunger signaling that's what's important and what's really interesting is that if you go to very low calorie diets as you start to refeed what you can see is that the the the cravings don't go back so they start up out here but even after six weeks of refeeding the cravings have gone away so you're sort of reprogramming your body for that so this is the again the changes so when you compare see R which is calorie restriction to alternate daily fasting if you look at the box what you can see is that the guerrilla is significantly different if you look at calorie restriction this one the ghrelin goes up by seventy one so you're more hungry after doing this calorie restriction the alternate daily fasting is only up by I think it's 16 but the p-value is 0.5 which means it's not significantly different again the calorie restriction daily calorie restriction causing more hunger the alternate daily fasting causing less hunger and that's a huge huge huge part so if you look at long-term weight loss what you see is that chronic calorie restriction cutting the fat cutting your calories eating six times a day so you're keeping your insulin high but dropping your calories what you get is an increase in hunger and a decrease in metabolism and this is what happens your weight plateaus your weight starts to regain and you're like oh don't even look at me right as you as you face that sort of you know all that judgmental people who are like oh yeah you shouldn't have regained that way it wasn't their fault because we know that this is all physiology as opposed to fasting where your hunger decreases your metabolic rate stays stable or goes up and you're like yeah let's go so that's the whole why don't we actually do this for people right it's because there's so many myths with intermittent fasting people say well you shouldn't do this you shouldn't do this you're gonna burn muscle right that's one of the more common things I hear if you don't eat you're gonna burn muscle and it's actually not true if you look at studies for example this study where they compared fasting so it's 70 days of alternate daily fasting you can see that the fat mass has gone down from forty three point five to thirty eight point one and the fat free master your lean mass went from fifty one point nine sorry fifty one point four to fifty one point nine so in fact your lean muscle is being maintained again remember what you're doing is you're dropping insulin and raising growth hormones so that when you eat you're gonna rebuild that protein so you're maintaining that lean mass if you look at this study again from 2016 if you compare the the two groups calorie restriction versus alternate daily fast and what you see is that the truncal fat mass is much better with the alternate daily fasting so one point eight percent versus 0.3% and this is the really dangerous stuff right the fat that's carried around your belly so that is like six times better but if you look at lean mass it's it's so calorie restriction is up by 0.5 percent because you've lost some fat but alternative daily fasting is up by two point two percent in other words it's like four times better at maintaining lean mass so this whole idea oh you're gonna burn muscle it's just a minute and if you think about it again do you think that our body is designed so stupidly that we store body food energy as body fat and when we need it we're gonna burn protein it's like yeah that's a good idea like you got to think that mother nature is so stupid we think we're so smart and humans are so smart and mother nature's so stupid you know we've been here for millions of years you you store body fat so that you can use it when there's nothing to eat you're not gonna burn your protein it's like you know storing all this firewood and then the you need something for your wood-burning stove you chop up your sofa and throw it in the fire like honestly do you think that's the human body like the human body is not that stupid and the other thing that people say oh yeah you can't do it right yeah that's great idea but nobody's gonna do it right it's like nobody like all the Buddhists that don't do it like all the Muslims you don't do it all the Catholics who don't do it all the Jews who don't do it I mean literally billions of people around the world follow this because of religion because of spirituality for whatever reason they do it millions of people have been doing this for thousands of years like at least since the time of like zero or you know aha Jesus when he said oh yeah you should fast like during Lent and so on like it's thousands of years we're talking of a human history that people have done it and Oh since 1970 it's a really bad idea because modern man is so smart and yet we got this obesity epidemic the type two diabetes epidemic and we still tell people you should never fast ever it's like that's ridiculous so it doesn't work is another refrain it's like well if you don't eat you'll probably lose weight and I put this in because some people say oh women it doesn't work in and it's like well it does because when you put them on fast women lose weight at the same rate as men it's it's it if you don't eat you're gonna lose weight and and the thing about fasting is that we're talking about something we're dealing with something completely different than diet okay so diet is something that tells you should I eat this or should I eat this right if I think I'm talked about that at all fasting is dealing with everything outside the period that you're eating so it has nothing to do with diet you can eat a high fat diet or you can do a vegetarian diet that has nothing to do with fasting fasting is really dealing with a completely separate question of when you should eat that is you should eat within a certain time or whether you should or shouldn't eat it's a completely different question therefore it's a much more powerful because you can add it to sort of any diet and that's really a lot of the advantage so it's flexible for example you could do it this week and not do it next week you could it's convenient because you don't if you don't eat you don't have to shop you don't have to cook you don't have to eat and you don't have to clean up and it's like honestly that's the reason I don't eat breakfast because I wake up at 7 I wanna be out by 7:15 so if I want a shower I'm not gonna eat and it's it's so much easier and my son does this and all the teenagers do this because they wake up so I wake up 20 minutes before I get out my son wakes up two minutes before he gets out the door right so it's convenient for people because you don't have to do it and this is one of the things we all have busy lives we all say oh you know you should eat a home-cooked meal every single time it's like that's a great idea but it takes a lot of time this is not that this is gonna actually give you back time so when I get busy I tend to do more because I have work to do it's free so this is a huge advantage like if you deal with disadvantaged people's if you're dealing with native peoples people who just don't have the resources to pie pastor fret you know pastor I pastor fed you know organic produce it's like that's great stuff but it's expensive like these people are not shopping at Whole Foods they're they got they got a budget and this is going to give them back money it's not just free actually gives you back money because you don't have to buy all this stuff and it's simple so again you can take these diets like ketogenic diets for example you can say well you know they're great but they're complicated so I deal with the 65 70 year old Filipino lady who doesn't speak much English and you know she's been eating this way her way for 65 70 years it's very hard to change her but it's a lot easier to say well these meals don't eat and just treat it like a medical therapeutic intervention you're gonna let your body burn off the sugar then you're not going to need your insulin and they understand that and it's simpler it is the easier it is and that's the whole point you can add this to any diet because it's not about the diet it's about a completely separate question so whether it's meat or wheat or nuts or you don't have time you don't have money you're traveling all the time you don't cook all of this stuff you can still use the fasting and one of the things that always appeals to the sort of doctors is that you have it gives you sort of this unlimited power because the reason why people like it is because if you have a drug for example like insulin you can prescribe you can give it and you know certain drugs have a maximum dose so you give metformin and there's a maximum dose people like insulin because you can just keep ramping the dose well fasting is the same like if you take a diet like a vegetarian diet and you don't do well well you can't get any more vegetarian to get better results right it doesn't work that way or if you're doing heated genic diet it's like you can't get more ketogenic because if that didn't work for you it didn't work for you that's the bottom line but with the fasting it's almost inconceivable that you can you can not lose weight because if you don't eat you have to lose weight so nobody doubts that it's just the the reason people tell you not to do it is because they say it's so unhealthy for you but it's actually the opposite is true and again we get back to this idea that you know what's so you know disconcerting about the whole thing is that these sort of ideas are not new they're actually the oldest ideas that ever came about like I didn't make this stuff up it came from Jesus Christ it came from the Prophet Muhammad it came from Buddha yeah the three most influential people in the history of the world like they only probably agreed on that one thing so we've practiced this throughout humanity throughout human history and yet as we get into the 21st century we think that our old selves are so stupid that it's not going to help you so you know these are these are like the oldest ideas in the book and and and they're so powerful and they're so and there's so much physiology behind it we've studied this for hundreds of years and why can't we do it right and the answer always comes back to there's no money in it there's no money in it like that's it and this is why these sort of things are so important to get these ideas out there because the point is not to make money I don't make money if you fast and do well I don't make any money but I get paid in a different way right same as bill we get paid in a different way which is that we understand that we're actually able to help move the needle for human health and we're allowing people to take control of their own health because if you have obesity if you have type 2 diabetes you're no longer have to say oh wow I have to go see my doctor to see what pill I need I need to go see my doctor to see if he needs to stick a stent in me no we're giving you the power to take back your own health because you're not gonna get it from anywhere else thank you thank you so much for that presentation so we are going to start with some questions from the floor and even you have a question that they'd like to ask dr. Fung Thank You dr. Fung that was wonderful I wanted to clarify a little bit about the caloric load and some of the different fasting approaches you talked about so let's say in a calorie restriction model they would have someone eat 1,600 calories a day down from a 2,000 calorie a day diet in an intermittent fasting type program would you still have them eat the 2,000 calories a day in a six-hour window each day or in the alternate daily fasting are they eating 2,000 calories the day they eat and zero the calorie the day they don't eat or how does that work yeah so that's a great question again the fasting only prescribes the amount of time that you're not eating so whether you eat all your calories in that time or you don't eat that many calories in that time is really talking about the diet so in most times I actually don't recommend people count calories I don't think it's a useful thing to do because the body doesn't count calories it's not a physiologic problem what you want to do is eat until you're full I mean they did that in the 50s and it worked out fine for them but what you have to do is really cut out all of these refined foods so a lot of the refined grains specifically there a lot of the sugar specifically so if you're eating things like meat and real food and vegetables and so on you're gonna get full at a certain point because again we think our bodies are so stupid but the truth is that we have multiple overlapping satiety mechanisms that is to say if you eat protein you're a whore moan called peptide why why goes up if you need fat cholecystokinin goes up if you eat a lot of fibrous foods you activate stretch receptors in your stomach so we have multiple overlapping mechanisms that tell us not to eat and they're very powerful because if you think back to a time where you went to the Chinese buffet and you ate a lot of food and so on and you said whoa I can't eat anymore like the sight of those pork chops might make you nauseated but half an hour ago you're gobbling them down right and that's because you've activated the satiety mechanism so you have to get back to that but the the sort of processed foods evade that so if you're eating you know you've had that big buffet and then you can't eat anymore steak but if somebody says well hey do you want this cookie you're like yeah sure because it doesn't activate those same satiety mechanisms so the point is not to count your calories because that's ultimately self-defeating you could take Diet Coke for example zero calories but it doesn't have zero insulin effect and it's gonna make you more hungry so the point is that during that six hour period you could take as many calories as you why I don't recommend people but stick to real food Whole Foods and your body will tell you when to stop if you decide that it's not working then you simply extend and say okay well that didn't work so I'll do a 24-hour fast and go from there but counting calories in general is not something I recommend so you might be getting the full amount of calories but just in a concentrated period of time but more likely you're actually going to reduce the amount of calories because it's hard to put all those calories so for example if you're mobile if you're fasting three four days you're not gonna be able to eat 15,000 calories and that one sitting afterwards so most of the time you're going to naturally restrict your calories all day you're gonna eat more so if you eat say one meal a day which is like a 24-hour fast for example chances are that meal you're going to eat more than you normally do but not like three times as much to compensate for the breakfast and lunch that you did didn't do but again stick to the real food stick to the full foods and you're gonna do fine because your body actually has the same mechanism that's why in the 50s and 60s nobody counted calories and everybody was thin because this is this is sort of a natural state you have to let people go but if you try and circumvent all these mechanisms by eating a lot of processed foods by eating constantly then that's why you're starting gain weight because you've circumvented the satiety and that's why you eat bread and jam in morning and then by 10:30 it's like oh I'm hungry and then the dietician says well the bread and jam was great because it is so low fat but then at 10:30 it's like go get a low-fat muffin so that's the problem you've circumvented those satiety mechanisms and now you're hungry again but if everybody knows if you eat steak and eggs in the morning oh I think that thing just sits there right it just doesn't move and then you're like 10:30 well I'm not gonna go get that low fat muffin because it's like what steak is still there because there are those natural satiety mechanisms so don't count your calories but you normally will when you cut the time it will naturally sort of come down anyway I just want to take a text question here real quick which I have heard you talk about before if someone has a history of eating disorders is there a risk that participating in intermittent fasting could trigger those behaviors would you approach the process any differently yeah so it's it's definitely a question of context so first the studies don't show that it does so we're talking about anorexia and bulimia so anorexia was a big problem in the 1970s people would actually die from anorexia and that was a big problem so the whole thing is that that's a it's not a it's a psychiatric disorder of body image that is people think they're fat but they're really skinny and the whole thing is that it's it's a matter of context so if you're 16 years old girl who's like 35 pounds sort of thing then yeah you shouldn't be fasting but the risk for example of this 60 year old 300-pound man developing anorexia nervosa is virtually zero so it's like yeah I'm not gonna fast this sixteen-year-old stick thing girl but this 300-pound diabetic man I am gonna fast so it's a matter of context so yeah if there is a history of anorexia nervosa then yeah you have to be cautious and you might try instead just to adjust their diets and so on and I always say that fasting it's it's a weapon right it's a weapon in the fight against obesity if you use it wrong it's it can hurt like it can kill you the so those people in the 70s when Twiggy was really popular and stuff like a lot of a lot of girls died it's like a serious problem but that doesn't mean that you shouldn't use it in the 60 year old man because he's gonna die of his heart disease or he's gonna die of type 2 diabetes in dialysis perfect thanks Priscilla please so excellent presentation could you speak to the data on intermittent fasting on the brain and cognitive function yeah that's really fascinating topic actually and there's not a huge amount of data but the it appears that intermittent fasting or fasting in general improves cognitive function which is you know a lot of people have the opposite and this is one of the other big myths so you know I have to work so I'm not going to be able to concentrate when you don't eat it turns out that if you do studies of memory and so on its improved so there are stories from you know antiquity so the Pythagoras the famous Greek mathematician for example would require his students to fast before coming into into class because it would improve their cognitive function and that's again because you're allowing your your you know instead of eating and all the blood sort of working on digestion you can you have that available for cognitive function and if you think about Thanksgiving for example if you say oh you had this big meal it's like do you feel like really really sharp afterwards it's like most people just want to sit down and watch some football because they're sort of sluggish they call it food coma and stuff so the cognitive function is actually increase I always look back there had that found I read this fascinating book called unbroken which is about prisoners of war in Japan and one of the passages they this this man who is who was literally starving says that he observes his his you know the other prisoners and and he says one is like reading a book a hundred percent from memory and another learn Norwegian within a week he says this is the astonishing mental clarity of starvation I'm like whoa like they knew about this like why didn't anybody tell us right so what's what's fascinating is that in Silicon Valley intermittent fasting is taken off like crazy and it's not because these you know 20-somethings skinny computer geniuses need to lose weight they don't but it's a very very competitive world and if you can increase your cognitive function it's the difference between Facebook and MySpace right it could mean millions of dollars so they're fasting because they want an edge and you know even in in sports you see this as well so we work with some elite athletes some of whom are like fighters for example and they're like whoa I can't believe it because I'm fasting and I can see everything right because their senses are heightened and why it's because the sympathetic tone is increased noradrenaline is increased so this is not because of some you know psychology it's because of real physiology they feel better they feel sharper and it's like yeah because think about it for a second if you're a fighter like an elite fighter like multiple martial arts or whatever do you want to be the hungry wolf or do you want to be that lion that just ate right because that line that just ate is just lying there in the Sun and the hungry wolf is sharp and so on so the cognitive function is actually increased significantly can it do things like prevent Alzheimer's that's a really interesting question I don't have an answer but my my guess is yes because again you activate this sort of process called at otha G which is where you're clearing out some of the old proteins including perhaps some of the protein that's clogging up the brain in the end you're increasing your mitochondrial health and all this stuff which it increases your bioenergetics of the mitochondria those cells that provide energy and you're able to increase it you see increased mitochondrial biogenesis with fasting for example increased turnover and so on so it's a very powerful therapy that's been used for many many years not because people thought it was unhealthy for you but because people thought it was extremely healthy we are running a little bit over so I want to ask you guys want to stay and do Q&A or do you want to go drink coffee yay okay I'm gonna go back to the text iron real quick obvious studies that show decreased prevalence of diabetes in the populations who have been fasting for religious and spiritual reasons for thousands of years this is a good question because they've studied Ramadan and I was talking with some dr. Seif read about this Ramadan turns out not to be very good so ramadan is the holy month of fasting you're not allowed to eat from sunup to sundown so the original idea the Prophet Muhammad was a very great proponent of fasting you're supposed to fast twice a week and then Ramadan and you're supposed to eat just a little bit to sustain you turns out what happens in real world sort of 2018 is that the people wake up at 4 a.m. gorge themselves and then they fast and then when the Sun Goes Down their drinking tubs of coca-cola and gorging themselves again and that's not really super healthy for you so unfortunately you don't have that data there is emerging data so it was just published actually last week I think where they use intermittent fasting strategies and what they found was that it could be just as effective as any of the other dietary therapies we've published some cases where people and implement these intrument fasting strategies and are able to get get off of insulin and so on because again it's not difficult to understand you don't eat your blood Sugar's come down blood Sugar's come down don't take your medications and pretty soon if you do that consistently you'll lose weight as you lose weight the diabetes gets better so it's it's a it's it works obviously and I don't think there's much doubt perfect we'll take a question from the floor sure thank you for the message I just wanted to share it's more of a comment than a question I we have been doing the intermittent fasting program in our prevention program in conjunction with it with a CrossFit box happy to report that over the last year that we've been doing doing this our patients have lost 1.25 tons of weight a fat and gained 478 pounds of muscle or lean mass during that time so there's a question from the text line what are your thoughts on carb cycling and fat loss meaning limiting carbs for 3 to 4 days then having very high carb days in cycles there's not really any good data so does it work it's possible you know I also tell people not to count their macros because again it's it's not your body doesn't know what you're eating it doesn't have carbohydrate sensors for example has insulin which is a hormone so it's but it's not just the carbohydrate so there are populations in the world like all kanawha for example in Kotova where they have studied this and people eat very very high carbohydrate intake so I come you know my family's from Hong Kong and China if you look at the 1980s they're actually eating mostly white rice and vegetable so if you look at the inter map study they're eating like 350 grams of carbohydrates per day almost all white rice then there's almost no obesity and almost no no type-2 diabetes but the difference is that they're not eating all the time there's no sugar intake and so on so you know I I think that cycling it is is possible as long as you're not still stimulating insulin and you know dr. Davis talked about the difference between say carbohydrates amylopectin a which is found in grains and beans which have amylopectin see it's completely different the physiologic effect is completely different but there's both still carbohydrate so you really can't equate the two that is eating bread I think is relatively obesogenic whereas eating beans is probably not and there's a lot of studies on eating beans and it seems to be fairly healthy so just to say carbs it's very different eating bread amylopectin a day and eating beans amylopectin C so that's why I say well it's it's it's much more complicated than just carbs like it's a good start but at the end of the day it's not the whole answer so if you're gonna eat high lot of teens then you're probably okay if you're gonna eat a lot of bread and sugar then you're probably not gonna be okay doing that but they're both still carbohydrates so it is a bit more complicated than that so sticking to again trying to make things simple which is again going back to the 60s it's like just a real food stay away from the sugar stay away from snacking don't eat all the time like these are the things like your grandmother would have told you we've got a question here yeah that's a great question again not a lot of data on that because they just haven't been done so we know there's clearly a link between obesity and cancer so the w-h-o classifies I think 11 or something two cancers as obesity related including breast and colorectal two of the most common cancer so we know in the lab for example there's a lot of insulin receptors on breast cancer for example but does that mean lowering insulin through intermittent fasting through low carbohydrate diets is going to work I think it will but is there any actual evidence not not a whole lot and the other thing is that my suspicion is that if you try to take care of it after the cancer has developed especially after it's metastasized it's it's probably not gonna be enough it is something that you want to use to prevent cancer more than you want to try and treat cancer with because I don't know that it's going to be strong enough to do anything by the time you get to that stage but there's clearly a link I mean the link between diet and cancer is just a fascinating one because again this whole focus of cancer medicine in the last sort of 3040 years cancer as a genetic disease I mean it's so wrong and so stupid like honestly I don't know how any intelligent person can look at the disease and look at the progress and think that we're doing well so you take a Japanese woman in Japan you move that Japanese woman to San Francisco and her rate of breast cancer will triple what and that tells you this is a genetic disease like nothing it's not a genetic disease right it's stupid but we do things like the Cancer Genome Atlas which sucks out like so much research dollars looking at oh hey we found this gene that's associated with breast cancer and all these little ol women are going out on their walks with their pink ribbons you know earnestly earning money and we're just pissing it away I'm looking at the genetics of this thing and it was not a genetic disease so why don't we instead look at some of these therapies looking at it from a new paradigm from a sort of metabolic mitochondrial disease State and one of the things I think too which is fascinating is the fasting it actually improves mitochondrial house so therefore could that be a potentially useful therapy to prevent the development of cancer because Tom says if you have mitochondria you if you have healthy mitochondria you don't get cancer so that's a fascinating thing but that the amount of research that has gone into it is sort of miniscule because we've you know found every single gene you know you know genetic mutation and it turns out there's like a hundred of them and the patient next to her has 100 completely different genetic mutations so how are you gonna treat that it's like where has there been any useful therapy so I think that the it's it's a fascinating question but unfortunately I don't have those answers yet and hopefully we can get some answers but we'd have to really start changing the thinking of a lot of the cancer cancerous like I mean of all the areas of Medicine like that's the worst one right they make the least progress of anybody we have one last question yeah so there is going to be a period of adaptation when you go from you know high carb low carb which is the keto flu and so on fasting is is sort of the same because if you're adapted to eating or if you're adapted to eat to fat metabolizing fat whether your fat comes from the steak or whether your fat comes from your body fat makes a difference so if you're on a sort of relatively low carbohydrate diet then your body will get the energy it needs so if you do muscle biopsies for example of people you can see up regulation of the genes that are involved in oxidation of fat so your muscle gets more adapted to fat burning basically that's all it is so during exercise your muscles should get whatever energy it takes I mean if you think about the any we for example who are eating all meat because there's no vegetables in the High Arctic they're able to do whatever they need to hunt those seals and hunt those whales and so on so your body will adapt to it but there is if you're trying to transition you have to be aware of this sort of two to four week period where there's an adaptation but after that again your body like you don't have to you know assuming that you have adequate fat stores and so again an average person has 25% fat so if you're talking about elite athletes even a marathoner is at about 10% body fat so assuming you have that then your body's gonna get whatever energy it needs from from your stores of energy so there's actually a big movement in a LEED athletics to do this so-called training in the fasted State so it's a it's a very very interesting idea because what you do is you fast for 24 hours then you do your workout then you eat and sometimes they eat a lot so we we work with some professional these who are eating sort of five or 8,000 calories at a time like a lot so the the point of it is that if you fast for the 24 hours what you're gonna do is you're in going to increase again sympathetic tone you're going to increase noradrenaline and growth hormone so the increase in the noradrenaline means you can workout harder than you did before because you're the hungry wolf instead of the sort of stated lion then you eat and your growth hormone is high so you're actually going to increase the the production of proteins because when you exercise you're breaking down muscle protein so therefore the bottom line is when you're talking about elite athletics what you've got is the ability to train harder and recover faster and we are talking about those sort of millimeters or whatever it's a huge advantage so we actually have a lot of people talking about doing that so it was sort of professional and an Olympic office because again they know that the difference between that multi-million dollar Nike contract and d-league sort of basketball is just a little bit so this this whole idea is actually coming around there's not a lot of data but the physiology suggests that this this sort of training in the fasted State is going to be a potentially useful adjunct to treatment like that is you know in when you treat people like there's no absolute so some people will love it and some people will hate it some people will respond well and some people won't but what we always say is that it's a therapeutic option so you even try it and if you do better on it then great if you don't do better honor then just go back to what you used to do because these are these you know you can change but yeah physiologically there's nothing to to block you from using fasting and some people are doing it deliberately to to increase performance you

Channel: CrossFit®

Views: 3,049,844

Rating: 4.8665481 out of 5

Keywords: crossfit, nutrition, home, at home, movement, functional, exercise, scale, modify, constantly, varied, fasting, food, diet, lifestyle, dr jason fung

Id: 7nJgHBbEgsE

Length: 71min 28sec (4288 seconds)

Published: Sat Jul 27 2019