Secrets Revealed: Doctors Expose the Mind-Blowing Truth About Fasting! - with Dr. Jason Fung

uh but but let's get back to let's get back to diet because you don't really need all of that although there's a role for it and so after doing a little homework I never really learned how you got on to fasting because for me it was seeing a couple people doing a low carb diet they and it clearly worked did you see some people using it or or or kind of got onto the the kind of face validity of it it was it was um essentially what happened was that so so as I was thinking about it I I was thinking that really the the cause of a lot of these problems is the hyperinsulinemia which is too much insulin right so and it's not necessarily the postal insulin but start to interrupt I was hoping when I said what causes insulin res resistance you would just say hyperinsulinemia yeah hyperinsulinemia yeah it's the same thing um as insulin resistance right so if you have too much insulin you know you're basically letting that fil cell fill up with glucose right you have high levels of insulin high levels of glucose you're filling up that cell with insulin and at some point right it's going to fill up and then you can't put any more glucose in so hyperinsulinemia the high insulin to me is sort of the big cause of the entire problem not just you know type two diabetes but also metabolic syndrome but also obesity because if you think about it insulin is a hormone and it's a normal hormone right and its whole job is to tell you to store fat like that's really a big big job of insulin it's not that it's a bad thing we need it to survive obviously but if it's too high like any hormone if it's too high is bad and if it's too low it's bad thyroid hormone parathyroid hormone growth hormone and the whole thing every single hormone it's neither good or bad it's just that the level is supposed to be in a certain range and if it goes to high it's bad so insulin is a normal hormone so there's nothing wrong with it but if it's in too high a range you're going to have certain dis diseases right and it's it's pretty logical because insulin its job so you eat insulin goes up as insulin goes up your body says you should store some of these calories because you're going to need it later when insulin goes down because when you go to sleep and you're not eating your body still needs energy so at that point insulin goes down your body now says okay let me burn some of this energy right so you eat insul goes up it says store energy you don't eat you go to sleep it's a fasting period you your insulin goes down your body says all right let's pull some of those calories back out and let's burn them for energy and that's the reason you don't die in your sleep every single night because your body has that ability now if you have a situation where insulin is high all the time and it's way too high it's much higher than normal levels well what's going to happen well you're going to store more energy because you're basically told your body to store more energy so there's two situations where you have to think about okay why is the insulin too high diet wise while either the foods you're eating are stimulating a lot of insulin and you have to remember that different foods will stimulate insulin to different degrees right that means that different foods will tell your body to either store that energy or not right and the other thing is is how long over what period of time are you telling that body to store right because if if it spikes up really high and then goes really low well you're going to start using it right so if it spikes up for one hour of the day and the other 23 hours of the day it's low well that one single Spike probably doesn't make an overall big deal of difference because it's low for the other 23 hours so that's why I thought okay well the diet is one aspect of hyper insulam but the other aspect is how often you eat and remember at this time it was like 2013 2014 people were convinced that you had to eat like 10 times a day like that was absolutely necessary for optimal human health even though in the past people never ate that way why because there was not all this processed food right like who's going to you know get up make yourself eggs and bacon in the morning eat it and then at 10:30 go and make yourself you know put you know make bake yourself a little muffing or something just for that right like don't you have to work right and so it was this whole idea that you had to eat constantly but in the past nobody did that like in the 1800s who was snacking constantly nobody everybody had to work in the fields everybody had to go you know to the factories nobody's stopping in the middle of the day to constantly eat nobody was eating in the middle of the day even if you think back to the 70s nobody's eating at their desk did you have vending machines in your high school no where nowhere if you if if you're hungry and was the middle of like it was 10 10:30 10:35 or you know is four o'clock after school you're hungry your mom's like no you're going to ruin your dinner right there's no after school snacks like you just sucked it up until dinner time you ate at those specific times because really there people are just too busy doing other things yeah I find myself saying it's okay not to eat so much yeah yeah so it it's not just the amount that you eat it's also what you eat because different foods have different insulin effect but it's also how often you ate because if you're not letting your body drop into sort of the low insulin levels then you're not burning those calories so you just saw food any food I mean some food raises insulin so just cut it all out is that how you got out well then I thought well okay so what if you cut it all out like that's the logical conclusion as to what it like how far to take it right and so then I thought oh what a bad idea right everybody knew that you had to eat 10 times a day that was just sort of a given uh this is 2013 2014 and so I was thinking but then I thought about it's like well wait wait wait wait a second so I think that it's really bad to not eat for you know 14 16 hours of the day but wait a second as a physician I tell people to do that all the time right so if you want to you know you come into Hospital you have pan pititis NPO right nothing nil pero you don't eat if you're preop you don't eat if you're postop you don't eat if you go for colonoscopy you don't eat so NPO n nothing per oral right yeah per oral yeah and and even if you did fasting blood work you had to fast if you didn't ultrasound you had to fast so literally every every working day I'm telling people well you got to fast for your blood work you got to fast for your ultrasound you got to fast for your colonoscopy you you just had surgery you can eat like literally every day I'm telling people four five six times a day not to eat did anything really bad happen to their metabolism no not at all and it was very funny because I remember at that time I I was taking a lot care of a lot of post ICU patients and people in the ICU were very sick they'd have pneumonia or something they'd be intubated you couldn't feed them for different reasons and they' go in on like a hundred units of insulin and they' come out and they' Beyond nothing no insulin their diabetes was completely gone because their sugars were completely normal and then they started eating again but their sugars were still normal I was like whoa what happened like why did they go in there with like so much insulin requirements and they come out with like none and it wasn't happening like you know once or twice I'd see it like at least once or twice a month I'd see these cases I was like H very interesting um and what could be the cause of it and that's where I start to think what's the mechanism and so on that that's that's where I started to realize that hey fasting is not that bad for you in fact they can be very good for you in those situations where you have too much glucose I had the great Fortune of going around with adapt your life my company and do Saturday morning events and there would be 300 350 people there in Pre pandemic and I would ask for a couple meetings I as how many of you have ever gone a day without eating nothing nobody and you know and how many of you have ever seen someone else go a day without eating maybe a few hands because in the hospital we saw it all the time yeah people were too sick to eat yeah and so the the common experience shared experience now is that we've always eaten all the time yeah and and and you're telling people not to that seems weird it was very weird so as I started to talk about so so then I went back into literature and thought what's so bad what's really so bad about not eating for 16 18 20 24 hours even up to several days right and and when you go back in the literature you quickly find that there was actually nothing wrong like you can find nothing WR unless unless there should be all these studies showing people dying left and right right yeah now there there were in the 60s actually a few um but they were like crazy these studies were crazy like in the 60s you did you know there's no research ethics boards and stuff like they did crazy stuff so there were a few people who are not like they take people who are pretty skinny already and then fast them for like 30 days or something like that right and it was like okay that's ridiculous I remember reading one study um in I think it was uh nine nine patients or something like that right they fasted them like nine days uh or something like that and these are skinny people right they didn't have a lot of these people skinny people they' fast them like nine or 10 days nothing to eat nothing to eat at all and then they gave them a big slug of IV insulin and it's like why why they just wanted to see what would happen well I mean you could probably do that again under close monitoring but that reminds me of of anel keys and at some of our meetings you'd say anel keys and there' be these booze in from the audience uh as one of the you know evil people in this whole story but anyway he did the starvation studies where the idea was what do you do when someone's been in a concentration camp post World War II and the refeeding was an issue all those coincidences one of my choir members I sat next to him in a in a choir I was in here in North Carolina had been in that study years ago with Professor Keys it was an amazing coincidence but that probably got starvation a bad name in the yeah it did and the funny part about that study if you read the the biology of human starvation which is the study found up wound up publishing in the 50s it was actually their diet was actually 1540 calories which is and and it was a very lowfat diet because they wanted to replicate what was available in post World War II Europe so they had high high starch because remember protein and fat are are relatively expensive right meat is expensive fat is expensive so people were eating turnips and all this other stuff so it was a lowfat diet 1540 calories a day which was actually 40% less than the Americans were eating at that time but it's like that's actually what most experts prescribed for decades right you're supposed to cut 500 calories you were supposed to eat 2,000 calories you're supposed to cut it down to, 1500 and cut the fat so that was that that starvation study which showed how bad it really was was actually what we had been taught to prescribe for decades and decades and then we wondered why everybody was going crazy on these diets and it wasn't working well we proved it like 50 years ago 60 years ago well and now I have to say from your Vantage Point in Toronto I think you have a more worldly view than us typical Americans who you know who think the whole world re revolves around the US you started incorporating the idea that other cultures or in religions fast and and what about that tradition what what have you learned it's actually yes that's what's very interesting because you know ultimately people have been fasting for thousands of years if you look at really any major religion they all have traditions of fasting so if f in was really truly so bad for us well we should have figured that out sometime past survival yeah that's right we wouldn't have survived and if you think about it like if you don't eat so your body has this ability to store energy which is calories right you can store it as glucose right you can store it as glycogen in the liver or you can store it as body fat either way those are the body's ways of storing energy so if you don't eat your body is going to use either the glucose or the body fat because that's a source of energy and that is precisely the reason you have body fat you're it's not there for looks it's there for you as a source of energy in case you don't eat so you're simply providing the situation where your body needs to go into its stores and burn off the glucose so if you're type two diabetic and you have too much glucose hey your body is going to burn off and that's good you're not going to need those drugs and I have no problem with those drugs right I I prescribe a lot of drugs as a physician but you can do it completely naturally for no cost right and if you have too much body fat you can do exactly the same thing and force your energy to use its stored sources and in in other words what you're trying to do is force your body to eat its own glucose and eat its own fat that is already stored away and that's natural historically and and I value the looking back you know we can have information or or even current cultures how long do people fast the the Indonesia I gave a talk there and learned from some doctors there they combined the daytime fasting with nighttime keto and they have a group called keto fosis Indonesia and they um actually that's where I first learned about keto babies I didn't know that was a term and there these are moms who do keto diets Who and the pediatrician I met and it's just anecdotal of course that that the babies are do great when their moms don't eat carbs or as many carbs but so historically did you know I think of Jesus going out in the wilderness 30 days or something I mean did did was it just daytime fasting or was it total fasting or water fasting and now I'm learning all these different names yeah it's all different so you have the um you have different fasting Traditions basically so you have say the Greek Orthodox who have different fasts and not sometimes what they call fasting is actually they don't eat meat for example they're they're cutting out One S you have um say the Muslims who do Ramadan and they will do they won't eat from sort of sun up to sun down so it's it's probably like what 12 14 hours 16 hours but they they do do a dry fasting which means that they don't drink water either um you have say Buddhists will often eat not eat after say 12:00 like noon time until the next day so they're going sort of like 18 hours something like that um so you have all different fasting Traditions um some some you know Jews have their fasting tradition on yam Kapur uh during Lent there are certain fasting traditions and people do different things right sometimes it's only like remember fish on Friday sort of thing that was a not a form of fasting but a form of sort of dietary alterations on those days um you know so so there are different fasting traditions and you know I I I go to a a Catholic church and you know every time around around uh Easter they actually talk all about fasting right they're like you know it's the the passages they read they're all about fasting and so on which I always thought was very funny because at the time 2013 2014 when everybody said oh fasting is the worst thing you could possibly do to your body you know all the time I'm in church I'm listening to the pastor talking about fasting a week why you should why you should fast and how it's good for you how it cleanses you and it's interesting because when you think about fasting it was always tied into this idea of it being a very healthy tradition that is it wasn't fun nobody liked it it wasn't you know it wasn't for a good time but it was something that you should do on a regular basis to sort of keep you healthy and um like even word itself breakfast right it's like the meal that breaks your fast what it implies is that you have to fast in order to break your fast you can't be eating all the time I that took decades for me to break apart that word breakfast and it's breaking the you don't want to break the fast so now um the what should we eat then and and this is where we're I I really want to get your opinion and ideas because the NIH group one of them at least that studies fasting intermittent fasting has them eat I mean a high carb meal once a day and and the results were not all that great for weight loss and so so my Approach is to teach you know low carb under 20 or 30 total grams per day people fast from within meaning they might eat once a day and all that but but so how do you work in different how do you look at the macros and and and doesn't matter I mean could you do the Skittles fast you know for a month yeah like you theoretically you could and uh you probably won't get all the benefits of the fasting because you're you're you know you're eating stuff that's relatively let's talk about let's talk about the optimal diet I mean getting your Bel I would I would agree cutting down the refined carbohydrates particularly is probably you know very very important I mean the the whole thing if you look at weight loss I mean you know people who need to lose weight or people who type type two diabetes you have a situation where your insulin levels are too high we know that like obesity is is is associated like when you measure the insulin levels of people who are obese they are definitely higher right than normal so same with type two diabetes it's actually a spectrum so obes you have normal people whose insulin levels are sort of normal then obesity where they're high and then pre- diabetes where they're higher and then type two diabetes where they're even higher than that so we know that hyperinsulinemia is and obesity and type two diabetes all go together so if your insulin levels are high then you should eat foods that don't raise your insulin level so much like I'm not sure why it's so controversial like well well but there's a two-step process right there carbohydrates raise the blood glucose and is it sugar or is it glucose I mean and in that r the I mean it's hard to there's just enough things to make it hard to understand but so I wish we go back to say sugar diabetes what well if you think about carbohydrates carbohydrates are sugar that's just had conversation recently I had to draw out you know G attached to G attached to G this is what a starch is yes glucoses all together and our bodies break down so I most of us don't get much nutrition training yeah most often either right and and again it's not that hard to understand when you actually break it down to type two diabetes you have too much glucose right so sugar is a nebulous term because it can include fructose which is a different type of sugar but let's just talk about yeah don't get me on that distraction but if we just talk about glucose glucose which is you know blood glucose is blood sugar right so fructose doesn't circulate free in the blood so blood sugar is blood gluc glucose so glucose and if you look at carbs so Brad rice potatoes they're all glucose so you take a highly refined because remember in nature nothing is sort of 100% something right it's all a mix of stuff so if you look at carbohydrates so highly refined say wheat uh you take the wheat berry you take out all the the fat you take out all the protein and you're left with 100% carbohydrate which is the flour now now that flower or the is basically all glucose it's arranged in Chains and you can go down through the biochemistry it's arranged in two forms amalo and Amal optin and those are broken down into glucose so it's just glucose so if your blood glucose is too high as in you have type 2 diabetes your blood glucose is too high why would you want to eat all that glucose because you could eat an egg which has zero glucose has protein which is amino acids it has fats but no glucose something's happen though where where I can teach this and the people don't believe me they want me to prescribe them a glucometer now that you know the cgms you can get them they're about $100 a month if insurance doesn't pay and people want me to prescribe GL because you need a doctor's order and they'll pay $100 a month to test out what I'm saying and so then they'll come back what did you learn well I learned that if I eat the things you told me not to eat it my glucose would go up see I guess you know there's a a disconnect between not um believing what doctors say and I'm a doctor get because it's because the the the message is so muddied by all the other people out there including a lot of doctors who say oh you should eat you know low low fat and lots of carbs right oh it's all about the calories like this bugs me the most it's all about the calories it's all about the energy it's like it's all the same it's like how is it the same like there's all these people out there that are all about calories calories calories David David lewig did the article that brought together the calories in calories out and the carbohydrate insulin hypothesis players together in the paper which basically said all of it you know it all matters at some point because you know if you do the Naked and Afraid diet where you're not eating anything total fasting for 21 days you lose a pound or two per day you know but I'm trying to get people to use lose weight in the healthiest manner so what should I eat that one meal a day then have you have you figured out um or is it really just up to what someone likes um no I mean there there are definitely things that I mean you have to take your own situation so again this is where I think it's very strange because if you have a situation where somebody is type 2 diabetic or overweight and wants to lose weight then cutting down the carbohydrate makes a lot of sense and intermittent fasting makes a lot of sense on the other side you have somebody who's not overweight healthy exercises a lot and then they go oh well I really need to go low carbon and do fasting I'm like why like your insulin levels are not high why are you trying to lower them you know there's no reason for you to need to do right I want to be in ketosis people tell me yeah yeah it's like but why right so it's fine want to do it the anti-inflammatory effects well you know the emerging science there well so do you have like a carb level or I I think in terms of total grams of carbs per day I I think about total grams too I mean I I usually try and tell people to stay under 50 grams so I'm probably a little bit more lenient than you um but on the other hand a book that has 2050 150 kind of the classic three tier carb intake and it's not to be honest even if you cut down to 150 most people are starting at 300 for 400 so even at 150 which we think is oh that's really hot for a lot of people they'll do extraordinarily well this is to accommodate the metabolism of people like one of my brothers who is naturally athletic and you know Burns all that stuff off as a he could eat up that eat up to that M many carbs a day but therapeutically yeah so the context matters for for diabetes under 50 total a day seems quite reasonable especially if you one meal a day or or intermittent fast it is that reducing the calories as well typically um it should I mean in in the ideal situation you will like the idea is not to take the three meals that you would have eaten and cram them all into a single meal right that's not the idea of intermittent fast hard to do the it's hard to do so that's good um but the idea is that if you normally eat say three meals a day and you drop one of them you should the other one should stay the same or as close to the same as you can get it and you know say you normally eat breakfast lunch and dinner then you drop dinner and lunch and you're only eating breakfast right so now you should eat as normally as possible during lunch and during dinner you're trying to force your body to eat the glucose that's in your blood or eat the body fat that's on your body so that you lose glucose so you can reverse type two diabetes or you lose fat so you can lose body fat right so that's the entire idea so if you simply eat more on the meal that you do eat well you're it'll still do you know you might do okay because it's really hard to eat a GI single giant meal compared to three right when you space them out it's easier um and and a lot of studies show this right if if you eat three meals compared to two meals uh like like one meal you know or six meals like the more often you eat the more likely you are to eat more total right that's and I hear that of natural people people tell me when I have breakfast I want to eat more that day which doesn't make sense if you're thinking of a a fuel tank in a car fueling up but it makes total sense if you think about if you come up an animal you kill it you eat it you know it's not like so eating makes you want makes some people want to eat more yeah once you start it's very hard to stop sometimes right because that's the way we're all built well definitely with junk Foods you know the highly sugar and alter processed foods for sure well so would it be reasonable then in someone in my clinic my world my patients many of whom are are watching that if they can't wrap their head around a strict perfect keto diet if they incorporate the F intermittent fasting the one meal a day idea uh and have a little carb just that one time a day if they can stick to it you might get the metabolic effects yeah yeah I mean the whole idea is that they're all you know part of the equation right so if one part cutting the carbs doesn't work for you at all for whatever reason right there's lots of different reasons people's diets preferences whatever my mother makes me eat it yeah then you can alter another part so say you do H you can't cut the carbs very well then you can Tinker with the fasting right they're all different things or if you do have carbs maybe there's something else you can do change the types of carbs so that they're not so refined right so there's different ways to change it so that it works out for you and um but I think you know the the cutting out the snacks is sort of a giant like because snacks weren't part of the sort of regular diet of people until the last 30 40 50 years that part can be moved back because that's more of a societal thing rather than um we really want to do it and that was one of the big things I was I had fought against in 2013 2014 was that idea that we needed to snack constantly to lose weight as then like you need to eat eat eat all the time to lose weight I'm like how how do you expect that to work like honestly like how do you lose weight while you lose weight you eat less I I find myself saying that it's like crazy well now um Switching gears totally then we got to wrap up this is so great can I have you come back some other time keep talking um really great to to talk to you um now in the US other countries there's really no one who's been sued in the US for doing this despite people saying that it's not true but other doctors in other countries have been in hot water from their Professional Standards boards and all uh Tim noes and South Africa Gary fety and Australia have you ever gotten into any t entangle I me serious ones not just trolls on the internet but yeah no luckily I haven't and um part of it is because I think I focused a lot on the science and just education rather than like just explaining rather than saying You must and and you know I think Tim noes were and and Gary both were unfairly targeted truthfully um you know that was honestly it was a it was a total Witch Hunt like that those stories are awful they're just awful but I know a few Canadian doctors who are who've been in hot water although they it's just been a hassle and they've been able to work it out but uh that's sad to see I I would hope by now 2024 that organizations countries realize that there are a lot of different ways to do this and you're you're really just kind of a I don't know py of someone with a different agenda other than science and helping people if you go after someone saying what you do and what I do now and last of all the textbook on keto diets ketogenic diet is out thanks to Prof no and the nutrition Network so um well that's good to hear and what would you want doctors to know I think I would want them to know for type two diabetes like even if you look at the American Diabetes Association nutrition guid lines they've actually completely changed right they um so low carb uh cutting down the carbs used to be this sort of you know very Fringe sort of way to do things if you actually read the guid lines they State like the low carb diet or cutting down the carbs is the diet with the most evidence like the most evidence like not Mediterranean not lowfat not low calorie it's low carb has the most evidence of any diet that has been scientifically studied for improving type 2 diabetes for fasting they basically say uh there's not a lot of data which is true but they do say that hey this is a very promising area and um in fact it's it it may be a way to achieve your nutritional goals but without counting calories or counting carbs so it's like okay well that's pretty a pretty good endorsement given that there is not a lot of you know hard evidence at this point but but it's like you're the best cello player on earth and you just play at your home nobody knows about it unless you go out in public they should be doing public service announcements with this know ridiculous right I mean it's it's crazy because it's like low carb you know so here it is the Ada right so what we all reference uh you know as standard normal Physicians will mostly reference the Ada in the UN United States right for diabetes they're saying it has the most evidence yet they don't they don't say it and even when you bring it up and big organizations like level two and United Health people are like really like they're like they're like stunned I'm like what it's there all there how we get information you know they need to have their you know push it out on on Tik Tock or or I don't know it it uh that communication of getting information out is a whole another thing but thank you so much for for all the work you've done and with in your YouTube work which is all available for free you know that people have to remember that and um I just want to wrap up by saying thanks and I was really good to know really good to talk to you about what uh you can do as a physician when you think about the Upstream going upstream and stopping people from jumping in the river that then they get all of these these consequences um any final thoughts for for my patients now I know you if you can imagine your your patients um just maybe a few thoughts for them I think the the the most important thing is to remember one it is type two diabetes is a reversible disease right so that's really important and again it all changed around 2021 right that's when the Ada first published criteria for remission which says remission is possible so it's not like you know the the reason reason we struggle is because we've been taught for like as as Physicians we've been taught for like two three four decades that it's chronic and Progressive and they've only changed it since 2021 right that's like two and a half years ago that's why nobody says it that's why none of the dietitians know it none of the nurses know it none of the Educators know it because it's relatively new but you have to remember it's reversible so therefore it all changes so the goal of type two diabetes care is not management as you say it's reversing it you should try to not have this disease of the diets you want to try low carb has the most scientific evidence and intermit fasting can be a useful tool and that's basically straight out of ADA and nothing you will hear anywhere else so you know that's great information because it's immediately actionable for people to say okay I get it my blood glucose is high I don't want to be eating a lot of glucose makes perfect sense to me the foods that raise my blood glucose I shouldn't be eating so many of those that makes perfect and now the science is behind you The Diabetes Association behind you so you know so so now we have to figure out how to make it easy for people get them to follow it and so on right and that's not that's you know it's not to minimize the task but at least the task of sort of the science of it is relatively like moving all in the direction I mean when you started talking about this like you were a lone voice in the wilderness right it was like who else was around talking about it not a lot of people right it was it was quite interesting uh to go from that to where we are today right yeah come a long way thank you and how do people find you where where what's the latest place to learn from DrJason fun uh yeah you can go to my uh Twitter on DrJason fun you can go on YouTube just look under my name Jason fun um and uh there's lots of videos there I I I I switched over there's my books which are available anywhere that do obesity code complete diet to fasting the diabetes code so you can go to any of those and I also write a blog on medium. com um and you know just FYI medium used to let you read stuff for free but I've been using them for years now they don't but I post usually post a friend link so that if you just you know follow me on Twitter you can find that friend link and then get access to the article as opposed to having to pay for it through medium but I like medium. com because it's it's it's an easy place to keep my blog that's all and what's the company you're working with now again uh I work with the fasting method.

com that's myself and uh Megan Ramos who is also uh you know we we started sort of in our office together uh doing fasting for large groups and you know just now we're trying to take it to larger audience online and um yeah the fasting method. com has resources it has groups it has master classes it has individualized coaching uh available for people who want that extra help and of course it also links to all of our free stuff because hey if people just want to learn about it then hey we're happy to share everything we know Wonderful all great resources and thank you so much for your time let's talk again okay okay great thanks so much Eric bye byebye [Music] if you enjoyed this video be sure to like subscribe and hit the notification Bell and check out adapt yourlife academy.