"It Only Takes 12 Hours!" - Burn Stubborn Fat, Starve Disease & Stay Young | Dr. Jason Fung

i used to think you know weight loss is just about willpower it's about calories and calories out the energy balance equation is always true but people always misinterpret it to mean that just eating fewer calories leads to body fat loss it does not [Music] you have been sharing health information with your patients with people all over the world for coming up to a decade now you've helped so many people improve their lives improve their health with all that experience with all that knowledge i wanted to start by asking you what are some of the daily

things that people can think about doing that's going to help them feel better improve their health reduce weight if they need to but also reduce the risk of getting sick in the future yeah i think there's a few things i mean one is sort of to stop a lot of this sort of snacking that goes on um you know for a long time people sort of said oh you should eat sort of 10 times a day sort of thing right now make sure you get your snacks and stuff and i think it really sort of

drives us in the wrong direction uh based on uh you know the people who need to lose weight because unfortunately that's the more you know that's the majority of people these days and this idea that you should sort of eat all the time and being healthy is probably one of the most sort of damaging things that we've done to people it's not natural it's not what we used to do it's not it's what we haven't like we haven't done that for most of most of our history it's only been in the last sort of 30

years that people thought well you should eat six to eight times a day most of the time it was sort of two to three times a day maximum um with stipulations that you really shouldn't eat more than that and then now all of a sudden people are like oh yeah you should eat so you know all the time to lose weight i'm like how does that even work right like from a physiologic standpoint when you eat you're not losing weight you cannot be it's impossible so you know this idea that oh you have to you

have to do that it's sort of a very very modern idea that's been presented as scientific and all that sort of stuff i think it's really damaging because then people don't get the right idea that hey you can leave your body and you know it'll figure out where it's gonna get its energy from without completely screwing up the system sort of thing so i think that's that's one of the things i've sort of focused on mostly is trying to increase that sort of fasting period or if you're trying to lose weight using intermittent fasting that

kind of thing it's it's it's one of the things that i think makes no sense to me whatsoever yeah the next thing uh i think it's it's important to do is sort of put it on the schedule that is even things like eating it should be sort of scheduled it's all the unscheduled snacking and stuff that that really derails people so you're walking by and you say hey there's a you know a coffee shop i'm going to get a coffee then you see the go in the coffee and then you smell the donuts and then

like before you know you've got the donuts right so the problem is that you've got all these periods of time where you've got unscheduled sort of opportunities to eat and they're never really good for you you're walking you're in the office somebody has a bowl of candy out so you go and get some candy you go to the you know it was never on the schedule you have a meeting all of a sudden somebody's ordered a plate of cookies and before you know it you've eaten cookies right so there's all this sort of scheduled stuff

uh like unscheduled stuff and so you really want to just put it make sure you know when you're eating you make sure you're it's sort of like mindfulness right you're you're deliberately scheduling a time to eat and every other time don't eat right and it it sort of goes hand in hand with this idea that we should eat all the time to lose weight we think that there's no cost to it um or you know maybe you were the ones ordering the plate of cookies for for the afternoon meeting right and it's like it's not

necessary it never was necessary it's not doing anybody any favors so you know make sure that when you're eating you know it's sort of it's it's sort of on the schedule like if it's not on the schedule then you shouldn't be eating and it's it's it's the same idea as mindfulness uh behavior i love the idea of scheduling when you're going to eat it almost feels like a revolutionary act in the 21st century because there's such there's such food availability all the time you know we're always surrounded by food tempted by food and just this

very simple idea that put when you're going to eat on the schedule i think for many people it it may be the first time they've ever heard that before yeah it's it's sort of it's what your default is right so most of the time up until say the 90s the default was not eating so therefore you scheduled when you ate breakfast lunch and dinner all of a sudden uh based on no science really we thought we should eat constantly from the minute you get up to the minute you go to bed you hear constant refrains

well you know always eat breakfast never skip breakfast start eating immediately and then have bedtime snacks and have snacks you think about in i don't know in the uk but in canada for example if you send your kids to school they get like morning snacks they get after school snacks they get snacks when they go on the bus you know they then they play uh you know sports and somebody wants to give them snacks in between you know to give them energy it's like you know they have plenty of energy whether you give them sugar

or not and so the default all of a sudden became eating so you know it was it was strange because we went from a default of not eating you have to decide when you're going to eat to eating all the time and descent deciding when you're not going to eat which is bizarre yeah so you know it and and not healthy because if your baseline is to eat then you gain weight it's unfortunately there's no way around it you are a big proponent of fasting intermittent fasting and you've done a lot to spread knowledge of

that throughout the world over the past few years many people these days are trying to experiment with some form of fasting in your experience and i know you've got you know years of practical experience doing this with real life patients with busy lives you know busy jobs kids to look after all those kind of things what are some of the common mistakes that people often make when they try and do some form of intermittent fasting um probably the biggest one is sort of overeating when you fast like thinking that just because you didn't eat for

a period of time that gives you sort of carte blanche to eat whatever you want afterwards um sort of there's two important factors in weight loss is one is the foods that you eat and we talk about this all the time that's your diet right what you eat when you decide you want to eat so you know people are paleo and keto and vegan and whatever there's plenty of different diets and we argue about that all the time um but what a lot of people don't talk about is sort of the time you spend not

eating right and that's your period of fasting how long should it be how often should you eat those are just as important questions because it's more than half of your day it should be spent not eating so um you know if you if you get that part right that is you spend a period of the day not eating 16 hours or 24 hours or whatever you decide it still doesn't mean that you can just eat whatever you want and there's been several studies doing this exact sort of um sort of over feeding strategy that is

oh we'll fast for 16 hours and then let people eat whatever they want well it's it's a very unsuccessful strategy you want to eat still healthy still sort of good nutritious whole foods and combine the fasting it's not sort of like there's sort of like two levers right you want them both going in the right direction you don't want to go one up and one down that's just going to make it ineffective so you know and and that's one of the things that people don't understand because there are some rat studies for example that said

well rats you let them eat whatever they want and as long as they fast for a period of time they stay underway so therefore that should apply to humans too you can eat whatever you want that is if you fast 16 hours you can eat junk food and fast food and mcdonald's and all this sort of stuff it's like no you can't the pine is when you're fasting all you're trying to do is let your body use the calories that you stored away as body fat that's all it is so body fat is nothing more

or less than a storage form of calories right you take in food energy in the form of calories and your body stores some of that away that's when you eat when you don't eat or when you're fasting then your body is going to use the store of calories that you've put away right that's why you don't die in your sleep every single night because your body has the ability to store some of those calories away so that's all it is so it always boggles my mind that people experts are saying oh you know intermittent fat

is bad for you and it's like not natural it's like it's the most natural thing in the world yeah you're supposed to be cycling that's why you have this word break fast breakfast you're supposed to fast otherwise you can't break your fast but you're supposed to feed in your fats and then if you ask your grandmother she would say something like well you know you just got to give your time your body some time to digest the food that you've eaten yeah it's it's funny how culture has changed so much just in the last 30

40 50 years where this idea of eating all the time has become just so prevalent and it's really interesting what people actually do you know professor sachin panda from the salk institute i know when i last spoke to him he was sharing information with me from his app that people are tracking how often they're eating for and he said 50 percent of non-shift workers in the us are eating pretty much over a 15-hour period each day now technically it was 14 hours 45 minutes but basically 50 percent are easing over 15 hours he said under

10 of people that they were tracking were eating in under a 12-hour window now if we compare that to 100 years ago this is so abnormal isn't it this is this is so not how we have lived for for most of our revolution and i guess the question then is you know why is this problematic and when we say fasting or when you use the term fasting what do you mean by it yeah and it's really just fasting is just any period of time that you're not eating i mean if you think about the 14

hours 45 minutes if you if you wake up at 8 a.m and you start eating immediately you're eating until 10 45 p.m right that's that's basically your entire waking day right minus brushing your teeth sort of thing right it's a ridiculous amount of time to be eating and that's the average so you know when you you talk about this how did you know how did this happen and why is it so bad well i think i have my theories about why it happened but the reason it's so bad is that your body really exists in

one of two states it's either in the fed state which is you're eating insulin is high which is telling your body please store some of these calories that are coming into your body because you're going to need them for when you're not eating or it's in the fasted state which is insulin is low you're not eating and your body says hey i need calories please take them from my storage right so it's no different than a refrigerator for example you go to the grocery store you have too much food you put it in the fridge

right so now think about it this way if you now go to the store five or six times a day and all the time you're putting food in your fridge putting food pretty soon your fridge is going to be full then somebody says well in order to empty your fridge you need to go to the store more often it's like does that make any sense when you're eating you're telling your body like you're literally telling your body please store some of these excess calories into storage put it into storage because that's what the insulin does

it's neither good nor bad it's just its job so because you're stimulating it all the time you're telling your body all the time to do it for 14 hours and 45 minutes of every day you're telling your body to do that and it's actually more because of course your stomach actually holds some of the food and slowly sort of pushes it out so it's not 14-45 that's your body is in the fed state it's actually hours longer than that so the point is simply this like we try and complicate things so much all the time

but it's very simple when you're eating you're storing calories when you're not eating you're using calories that's that's all it is and that's natural and it's normal and you can handle it like people think it's so um you know you need to eat 2 000 calories in a day you shouldn't cut your calories for example like what you know if you fast the entire day well if you're worried about those 2000 calories well what about the 100 or 200 or 300 000 calories that you have stored currently on your body like why would you worry

about the 2000 just like the refrigerator if you don't go to the store one day are you going to be really badly off well your fridge is overfilled you have way too much stuff in the fridge just eat something from the fridge that's the same thing if you don't eat your body has a you know 300 000 calories of body fat your body's gonna use it or you're diabetic you have blood sugar sort of is spilling out from everywhere your body's going to use some of that sugar because it's a source of energy so what's

wrong with that how is that bad in any sense yeah of the word you're simply letting your body use it for what it was designed for and that's the whole point of fasting which is why it always boggles my mind that you see experts saying oh you know intermittent fasting's so bad for you but you have and there are certain circumstances of course if you're malnourished if you're underweight you know sure absolutely but if you're overweight if you're type 2 diabetic that's actually exactly what you want your body to do yeah let's expand this beyond

weight loss because one of the things that pulls all of your work together for me at least is that we have overly focused on calories and not focused enough on hormones and it's easy to talk about fasting and burning body fat in the context of someone who might have type 2 diabetes or someone who is carrying excess fat and considers themselves to be overweight but this goes beyond weight doesn't it this is actually a very helpful practice for people who want to be in optimal health have more energy yes have a good body weight but

also reduce the risk of getting sick in the future yeah absolutely because if you think about it like it's it's a balance here right you eat you store calories you don't eat you use those calories right and you want to keep those in balance so 12 hours 12 hours is perfect if you think about a typical sort of 1960s 1970s because and i and you know i choose that time because it's before the obesity epidemic and people aren't really watching their diet particularly people are eating white bread and jam and you know stuff like that

right um but if you think about it you know you ate breakfast maybe eight o'clock before school and then you had dinner maybe around six o'clock that's a 10 hour eating window and 14 hours of fasting and literally everybody did that every single day without even thinking about it so was it hard no because that was sort of your baseline and the the point is that it's not um it's not neither difficult it's just about your habits and then um you know then all of a sudden uh people switch and change but before that you

would hear things like you know if you wanted an after-school snack your mom would say no you're gonna ruin your dinner if you want a bedtime snack she'd say no you should have ate more at dinner right so there was not this tolerance of snacking it was sort of this occasional thing that you did once in a while but rarely it's an indulgence right and then it became every day so you know my kids when they went to school on a trip for example a bus trip right they'd go on the bus and you get

this note from the school which would say please send two snacks with your child and i'd be like why are they not eating lunch or am i not feeding them dinner is that what i think is that oh my goodness and and and then we so we teach them that it's you have to snack all the time and then we blame them for gaining all this weight and then tell them that hey it's your diet it's your lack of willpower and it's like well you know we focus on the wrong things and you might say

it was all very inadvertent i think it wasn't that anybody deliberately meant to do that it it all came back to sort of the the dietary guidelines which was in the 70s people said you know you should eat ultra ultra ultra low fat and in order to do that the government the united states government encouraged people to eat processed food because you could process the fat out of it and put other things mostly carbs because fat and protein tend to go together and so instead of eating say a typical breakfast of eggs and bacon which

would keep you full until lunch they'd eat two slices of white bread and jam and some sugary cereal the problem with that and we know this of course is that insulin spikes up very high glucose spikes are very high because they're all very highly refined carbohydrates then it crashes so by 10 30 you're just starving so then you go get yourself a low-fat muffin and then the same thing happens right your your ins glucose spikes are very high your insulin spikes are very high and and then and then it's gone so people started eating more

frequently because they're basically just eating a whole bunch of refined carbohydrates then they said well i'm eating six times a day when i used to eat three times a day but since i'm eating super low fat this must be a good thing it never was a good thing of course it was just a byproduct now of course we know we shouldn't be eating a whole pile of refined carbs like right away but back then two slices of white bread and then strawberry jam was perfectly acceptable very low fat almost zero fat in fact all sugar

all refined carbs so i think that's sort of how it came about because of this uh sort of insistence that we eat low fat low fat low fat which unfortunately wasn't like more beans it was refined highly refined carbs is what replaced the fat in our diet but then the inadvertent thing was that even as we moved away from those refined carbohydrates so we started acknowledging hey there's healthy fats hey you should eat nuts hey you should eat whole grains even as we moved away from those refined carbs we never moved away from the fact

that we're just eating constantly and of course our institutions have changed to allow all that right so our habits have changed you have you're it's acceptable to eat at your desk it's acceptable to eat in the movie theaters it's acceptable to eat in front of the tv it's acceptable to eat while you're walking like all of those things would have been super frowned upon if you went to the office and you were eating at your desk in the 70s people would be like what the heck are you doing like there's a place to eat and

it's not at your desk go eat somewhere else but because everybody was hungry all the time you know you got this 2 30 i mean you've been to you've been to meetings like medical meetings right like my god it's like okay so you have a full breakfast then at 10 30 they roll out the you know the granola bars and stuff that's at 10 30 a.m you just ate a huge breakfast at like 8 a.m and then you have lunch and then you know at 2 30 there's a nutrition break right where they roll out

muffins and cookies and stuff right and then you go eat dinner it's like these are for doctors like you and me and this is at every single meeting you go to american heart association diabetes association like you'll go to the diabetes association meeting they're rolling out yeah snacks and snacks and snacks he's like okay well what's the message here eat all the time it always is and i think that just speaks to culturally how much this has changed as you say it's just acceptable now to do this in fact if you were hosting a meeting

it would probably be considered rudes if you didn't provide cookies and biscuits and those sort of things do you know what i mean very few of us are able to resist societal environmental pressures which is why what happens at school saddens me so much because it it literally is conditioning kids from a young age to you know think oh i need to snack i'm not eating for two hours i need to eat something whereas you know the truth is we know we don't need to do that and culturally there's countries where i think france is

still there in france where you know snacking is just not that common acceptable type thing to do you eat when it's meal times and you don't sort of eat in between and when i spoke to professor tim spector on the podcast he was saying very similar to you the impacts of constant snacking what it does for the gut microbiome all kinds of things that we just don't need to be eating all the time now jason one of the central ideas in your work is that chronically elevated insulin is problematic for a variety of different reasons

when was the first time you started to become aware of this as a doctor and then maybe you could go from there and explain what causes insulin to go up and what happens to us why should someone listen to this right now who doesn't have type 2 diabetes thinks they're in pretty good health maybe they've got a little bit of extra fat that they don't want but they can live with it why should they care about chronically elevated insulin it actually impacts a huge number of uh medical conditions it actually so if you look at

insulin resistance which is really the same as chronically elevated insulin they're sort of like two sides of the same coin right so it's called hyperinsulinemia which is basically a word hyper means high insulin and then emia means in the blood so hyperinsulinemia just means high blood levels but insulin resistance people have heard of is the same really as hyperinsulinemia they do the same thing and it really impacts a huge number of conditions such as heart disease type 2 diabetes which can cause then kidney disease nerve problems amputations cancers related to insulin levels so there's just

all of these chronic conditions that are really the main focus of today's medicine that are made worse by chronically elevated insulin levels and the point is that you're you're really not supposed to be in that state so when when you look at hormones and this applies to almost all hormones you're really supposed to have a spike of hormone and then go to low levels so whether it's thyroid hormone or growth hormone or cortisol or parathyroid hormone all of these hormones they spike and then they go down so growth hormone for example will spike in the

morning and then it'll go down to very low levels and that's why you have to measure these hormones at certain times of the day and not other times so you do an am cortisol in the blood work for example well insulin is really supposed to be the same you're supposed to have sort of high levels when you eat then it's supposed to go down and then at high levels and it goes down so you're always supposed to have this sort of balance between the two what's really bad is when you have high levels all the

time and that's true for cortisol as well cortisol again it's not bad for you it's just a natural hormone but you're supposed to have it spike up and then go down when you have it chronically high it's actually super super bad for you this idea that eating all that you should eat all the time of course leads to insulin levels being up all the time and the other problem is that as you move away from fatty foods and stuff then you're choosing foods that typically spike insulin much higher so if you're choosing white bread over

eggs in the morning eggs that have very little insulin effect and white bread has very high insulin effects so you know it's sort of a double whammy you're choosing foods that are very high in insulin and and and if you think about it so insulin its job is to tell you it's a nutrient sensor so it tells you food is coming in please sort away so you choose white bread so even if it's the same number of calories say you choose a white bread versus an egg when you eat that white bread glucose spikes up

insulin spikes up when insulin spikes up it says put all those calories into storage because that's that's its job that's what it's telling you to do so when you eat that bread it contains two things it contains the energy which is the calories but it also contains instructions as to what to do with those calories so you eat the white bread and insulin goes up all that energy goes immediately into your storage well now at 10 30 you have no energy left your blood sugars are starting to go very low so what happens your body

says i need to get more food why because you've put it all away it's just like you go to the grocery store and you take the food instead of eating some of it you put all of it into the freezer or the fridge well you have nothing to eat so then you go out and buy more food right it makes no sense whereas the egg the insulin is not going to go up as high the energy is now available for you to use all day and you're not hungry at 10 30 because you still have

energy to to to do your activities with daily living right but it was the hormones really that made the difference and this is the thing that i think is really important when you have two foods you know white bread and eggs which are the same number of calories the body's response to those calories are completely and utterly different okay so one of them spikes insulin one of them doesn't so in order to say that they are equal and you hear this all the time calories a calorie just count your calories right that's how you get

stupid ideas like oh you could eat ice cream for dinner just don't eat your broccoli because there's a hundred calories of broccoli you didn't eat so you can eat 100 calories of ice cream well that's stupid it's really really bad advice that a lot of experts gave out because they're like it's the same number of calories but the hormonal effect is so different and it's the hormones that tell your body what to do you take 100 calories in you can either store it away or you can use it as energy right one of them makes

you fat and one of them makes you full gives you energy which one do you want to do well you have to choose 100 calories that don't go straight to fat which is you know the ice cream and the white bread and so on right and that's the point that everybody misses when they're so focused on calories and there's so many people out there that are like dollars you're saying calories aren't important like i'm saying that there's way more important things than the calories because it's what you do with that energy not just the total

amount of energy yeah there's a couple of things there for me one of the problems with saying whether you're eating ice cream or eggs or salmon or whatever it might be it's the same as long as the same amount of calories problem number one with that for me is that food is so much more than calories food is information food has an impact on inflammation it has an impact on genetic expression it does so much it's it signals so many things in the body which we we really undervalue when we just say how many calories

is in that firstly secondly i think this idea of calories is worth just exploring in a little bit more depth because as you say a lot of people talk about calories in versus calories out it's simple if you want to lose weight or maintain a healthy weight you just need to get in a deficit with calories you know we have to be burning off more than we're taking in technically scientifically do you have any insight on that yeah so the energy balance equation is basically they say body fat equals calories in minus calories out that's

sort of the what we all think about so therefore people say oh you must be in a caloric deficit you actually can never be in a caloric deficit because it's a balanced equation there's three variables body fat calories in calories out and they must balance so the point is that if you change one of those variables and everybody forget i always think there's only two variables calories in calories no there's three variables body fat calories in calories out if you change one of those variables calories in it does not mean there's two other variables it

does not mean that your body fat will decrease because if you decrease calories in you could also decrease your calories out that is your metabolic rate will go down and your body fat will be unchanged right so the energy balance equation is always true but people always misinterpret it to mean that just eating fewer calories leads to body fat loss it does not in fact almost every study we've done over the last sort of 50 60 years says that when you simply reduce calories and don't change the sort of composition of your calories then what

happens is that body fat goes down a little bit but what happens is your metabolic rate goes down more so if you go from 2000 calories for example you're burning 2000 to eating 2000 your your your you know imbalance you want to lose weight now so you go down to 1500 calories that's what everybody says right eat 500 calories less per day so you cut out the salmon and you cut out the eggs but you love bread and ice cream so you keep your bread and ice cream you go down to 1500 calories there's two

possible things that happen one is that you lose body fat but two the other possibility is your body simply burns 1500 calories and your body fat stays relatively unchanged that does not break the energy balance equation neither does it break the laws of thermodynamics in fact when you look at studies every study we've done practically over the last 50 years shows that is precisely what happens you eat 1500 calories your body then actually goes down and burns 1400 calories and you start to gain weight back and then when you start to gain weight back because

you did the diet all wrong by focusing on calories people say oh you know you weren't trying very hard you didn't have willpower and all this kind of stuff right and that's the whole problem with weight loss is that when you focus on calories you're you're losing the sort of thread of the energy balance equation you think that eating fewer calories guarantees you body fat loss it does not you can just as easily balance that equation by reducing your energy expenditure just like if you are working and you get fired you lower your expenses yeah

that's just what you do so that you protect your bank account right you don't want to take money out of your bank so you lower your expenses so you reduce your income you reduce your expenditures so same thing with calories you reduce your income how much you eat calories in your body reduces calories out you don't control that yeah you can't decide to burn more calories but your body does yeah now all of a sudden you're in a situation where you're still overweight but you're eating 1500 calories and your body's burning 1500 so you're cold

you're tired you're hungry you feel terrible but you're not losing any body weight that is actually precisely what has happened and everybody who's done a diet knows this every single person the failure rate of sort of counting calories for weight loss the failure rate is somewhere around 95 to 99 and yet we think that this is the scientifically proven way to do things it's actually proven to fail it's guaranteed this is practically guaranteed to fail if you don't adjust the foods that you're eating because as you say we think it's all about willpower but really

it's all about eating the right foods because the hormonal response to those foods which is telling our body to either gain weight or not gain weight right that's that's what tells our body it's demonstrably different like you eat bread you eat an egg we can measure the difference in the hormones that you've stimulated right it's not just an airy fairy we know it 100 for sure that there is a difference and yet we have to pretend that those hormonal differences make no doesn't matter right which is ridiculous we'll be back to the conversation in just

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details at athletic queens dot com forward slash live more or simply click on the link below now back to the conversation you know the other thing i think people miss when they're focusing too much on that equation is that when we talk about calories out everyone assumes it's just one thing you know it's it's like how much did i exercise for example that day they forget that actually calories out could well be four different things the basal metabolic rate as you've mentioned so you know how much energy does it take to keep the lights on

in your body lungs kidneys whatever it might be there's also the thermogenic effects of foods and the whole context of things it's relatively small but still that's part of that calories out part of the equation there's purposeful movement and exercise which yes can burn some calories although potentially not as much as people think and then there's also neat you know non-exercise activated thermogenesis is a kind of non-purposeful movement all these kind of subtleties people are not thinking about when they're thinking about that equation so i think for many reasons while scientifically that equation may be

true in terms of practical application for most people that has very little value and i think i think this is a wider point jason for me which is there's a lot of technical scientific debate around these kind of topics insulin calories in calories out you know for me like you as a practicing clinician it's like well you know what yeah we can debate these little nuances in the science or we can simplify things and just help people do what we know and we see repeatedly work do you know what i mean and i feel that's

one of the the reasons i i very much like your approach you have seen tens of thousands of patients you've helped probably millions of people through the internet now and through your books across the world a lot of people are gaining huge value from this and i think we sometimes miss that when we're trying to dot all the eyes and cross the tees with the science it's important but it's not everything yeah absolutely and and this whole idea that you know a certain number of calories 100 calories of bread versus 100 calories of egg are

going to have different effects on the body they have different hormonal effects um it boils down practically to a simple idea that is some foods are more fattening than other foods which is of course an idea that your grandmother would have thought blindly obvious right like who gets fat eating broccoli like zero people in the whole world who gets fat eating cookies many many many people right and she didn't understand the difference between you know the hormonal responses of broccoli versus cookies but she understood that you eat these foods you know and this goes back

hundreds of years because the first low-carb diet was sort of like what banting in the 1800s right so you're talking about at least 150 years people have said hey certain things really make people gain weight and even if you go back to ansel keys for example so he did a very interesting study in the 40s the minnesota starvation study interestingly it wasn't a starvation study at all it's a 1500 calorie a day diet 1570 calories which is actually not far off of what people advise for weight loss very high starch foods because that was what

was available in post-war europe at the time so when he measured metabolic rate it dropped by like 40 percent when you dropped calories by about 40 metabolic rate dropped by about 40 percent and what happened he actually measured other things so heart volume shrank stroke volume like the amount of blood that you pump out went down people were cold so they're generating less body heat because they're burning 40 percent less calories you're sort of these sort of metabolic housekeeping things like how much blood to you're not pumping blood you're more tired you get you know

you you're you're not generating body heat you're cold right so the whole point is that yeah all of these things are important this calories out is not just exercise the majority of it is you know basal metabolic rate and you don't control that through your mind right you control that through your hormones it's your hormones that control everything that's just the way it works in the human body everything is controlled by hormones you don't control how strong your bones are that's controlled by growth hormone and other hormones parathyroid hormones right you don't control how active

your thyroid is so this idea that it's all about willpower you know because people look at this thing they go body fat equals calories in minus calories out so therefore calories in is what you eat calories out is exercise it's all willpower it's like that's nonsense it actually doesn't work for anybody because you have to actually it's an extremely simplistic way of looking at things when you go one level deeper and say okay so okay calories in minus calories out it's what you eat and what you exercise let's go one level deeper why is it

that you're eating more or eating the wrong foods well it's because you're hungry so that comes back to your hormones and then you look at calories out what's exercise let's go one level deeper it's actually mostly basal metabolic rate so you can control what you eat but you can't control how hungry you are you can't decide to be less hungry you can't decide that you're going to burn more calories so it's all down to your hormones it wasn't due to willpower at all so you can take a drug such as cemaglutide which is a weight

loss drug now when you completely whack that appetite you know in half people lose weight it never was willpower it was that you controlled the hunger as opposed to the calorie right it all comes down to hormones the human body is run by hormones that is that is the chemical messengers that tell our body what to do and and this idea that it comes down to something so simplistic like calories calories is such a terrible notion because it's not terrible it's just misused because it's a unit from physics not physiology right so it's the amount

of heat energy that is contained in a certain amount of food it doesn't tell anything about how our body is going to use it a block of wood may have a hundred calories if you eat that block of wood you will get none of it right so it's like well you know that's it right i mean there's there's there's lots of calories in a block of wood but you won't absorb any of it it's just a unit of physics physiology is what happens in the human body right where are the calorie receptors do we have

calorie counters within our body that's like you took this many calories there for this right and you look at the failure of that sort of academic notion that we can be so precise that we are now physicists not physicians right like we're physicians that sort of stuff from physics doesn't work because it doesn't jive with how the human body works we don't have calorie counters we don't have calorie receptors like there is nothing in our body that senses how many calories you eat and it doesn't account for the realities of modern life where people are

sleep deprived right and therefore their hunger and society hormones are completely off whack it doesn't account for chronic stress which raises that hormone you mentioned earlier cortisol which again has a huge effect on our hunger and all kinds of things and where we might store that body fat you know the human body is just much more complex and i think i think a lot of people have a certain bias right so if you're a personal trainer i guess your bias is probably the subset of people you've seen people who are coming to see you who

believe that actually working out regularly exercising hard is really really important to lose weight and of course it can form part of the overall strategy of things but therefore your view as a personal trainer is going to be hugely impacted by what you see of course my view is hugely impacted but what i've seen over 20 years tens of thousands of patients but as a general practitioner i guess one thing i would say is that you see everything you literally see everything you see you see people who've got all kinds of issues and therefore i

feel that gives you insight into a whole variety of different people different lifestyles people who are shift workers you know and you you know you're a practicing clinician as well i guess as a nephrologist you will also see a huge amount of different people right yeah exactly and that's uh one of the things that you see a lot of in this sort of fitness world and there's this sort of pro science because you know you're so invested in this idea that it's all about effort right you know that that that all of weight loss is

just due to effort and willpower right as opposed to you know eating the right foods and all these other things that are so important we know like sleep and stress and so on um i i used to you know and i think we all did of course we all used to believe that right now i always thought in medical school and above i used to think you know weight loss is just about willpower it's about controlling what you eat right and i always thought it's strange that there are a lot of medical conditions that cause

weight gain weight loss but weight gain in particular and i always thought it was strange because how can a medical condition cause weight gain it's all about willpower 100 about willpower it's about calories and calories out i i used and then i thought how is that possible that you have a medical condition that has nothing to do with willpower right so if you're if you have crater willie or any of these other conditions that cause obesity um you know addison's sorry cushing's disease how can that cause weight gain because we know that it's caused by

sort of effort right so it's very strange but as you go on then you realize no it's all about it's all about the hormones like you give somebody insulin and i don't really care how much willpower you have you gain weight why because you're literally telling your body to gain that weight so therefore if that's the important thing then how are you going to minimize those instructions to gain weight while you eat natural foods because natural foods even carbohydrate-containing foods natural ones have far less insulin effect than others yeah and intermittent fasting when you don't

eat you know your your body is going your insulin levels are going to go low your body is going to start using calories instead of storing calories right so it's all about those those those hormonal effects that we have to understand that we said were unimportant because we sort of elevated calories to be the one and only thing and i think a lot of fitness people and a lot of scientists in fact love the sort of simplicity of that idea but unfortunately it wasn't really true and you see it um yeah all the time like

there's so many people like doctors for example there are a lot of doctors who are overweight and i know a lot of doctors most of my friends are doctors right and would i say that they have no willpower absolutely not i've seen these people work sort of 36 hours at a time right when they put their mind to something they will absolutely go out and do it nothing will stop them yet these people are overweight some of them are obese some of them are my friends i don't think they have no willpower i don't think

they have a lack of willpower as the reason that they are overweight i think they're eating the wrong foods because they or or they're getting the wrong advice to eat constantly and so on and so many doctors have come back to me so when i started talking about intermittent fasting probably about eight years ago like honestly people thought i was insane like it was you know common knowledge that you had to eat all the time even to lose weight right and when i came out and said well you can fast i mean and and and

most of the doctors that that i spoke to you know because they knew me and they would listen to me they said this actually makes a lot of sense and they're all like you know i remember when i was in residency and training i'd go like 24 hours without eating nothing bad ever happened i was so busy in the emergency i was so busy in the operating room at so many patients i just didn't eat and nothing really happened other than i was hungry for a little while but i was too busy i ignored it

and i'm thinking yeah because when you don't eat your body is just going to take whatever calories it needs from your body fat and that's it and everybody's like yeah i was like 30 pounds lighter at that time right when i didn't eat constantly so a lot of a lot of physicians would always come back and say you know what this makes a lot of sense from a physiologic standpoint this idea that you should eat all the time is wrong so one you know fasting is a way to eat fewer calories because you're taking it

from your stores and you're feeling full because you've taken it from your stores right just like you take food from the fridge it doesn't mean you're less full you're just as full as if you went to the store just you took it you took those calories from a different place you took it from storage same thing with body fat you took those calories from storage as opposed to from food yeah no difference in terms of physiology so yeah it's interesting because a lot of doctors themselves even these sort of highly highly educated people would say

and and and that's the that's one of the things that um you know i think has has started to sort of resonate through uh there's an interesting study where they looked that they did a they did a facebook poll of physicians and how they lose weight um and what was interesting was that 75 of people used intermittent fasting in this poll for weight loss physicians yet they only canceled it for about 30 so the huge gap was that the doctors wanted to lose weight and wanted to do something effective which was fasting but with their

patients they had to give sort of sanctioned advice which didn't include the fast i want to get into some practical information for people i think one of the really beautiful things you said so far is that it's not a lack of willpower and unfortunately this over focus on the calorie has led to a lot of people feel really bad so that they they think you know i'm really trying like i'm restricting my calorie intake um i'm not eating that much but i can't lose weight and they feel like failures i feel guilt they feel ashamed

of themselves which is really really toxic to try and make long-term behavior change when you feel like that so i want to go into some really practical things before we do just to finish off the calories and calories out model for a moment my approach has always been with patients and and when i like you when i write books i say look if you find that counting calories works for you and you can fit it into your life and your lifestyle and you're getting the health outcome you desire i'm not trying to change your mind

i'm not saying stop doing it if that works for you go for your life i'm just saying in my experience i haven't found it to be that helpful certainly for for most people that come to see me what would you say to someone who is watching this says jason listen um i actually have no problem counting calories i like counting them three times a day and i can maintain my weight i can maintain my health doing this what would you say to that person i i agree with you i mean if something's working for you

then go ahead and do it like there's no reason to stop and um you know it really goes for any anything it's it's it's uh if you're eating 10 times a day and you're doing well with it then go ahead like be my guest and we know every everybody reacts differently so i'm okay with that but if if you want to make a change then you know you could probably go to that's where to start right here is a good place to start and then you decide what to do with it and i think the

other thing you know i think you said that was very good was that this idea of um sort of people who aren't losing weight what happens of course is that when you focus on calories and say it's all about willpower what you're saying to these people is that they don't have the willpower which i think is absolutely not true because it's it's one of these embedded assumptions in the calories and calories out model that is that nobody acknowledges which is that calories out can go down your basal metabolic rate can go down when you diet

so therefore if you are not losing weight even as you lose as you eat fewer calories you could still not lose weight because your metabolic rate is going down along with it so why are you blaming these people and that's that's where you get a lot of um you know a lot of people sort of just have made that assumption that calories out is going to stay stable at 2000 calories a day right this is the whole thing when you read these people who are like oh just just cut 500 calories a day you'll lose

a pound a week that actually never happens because that assumes that your calories out your metabolic rate stays at 2000 calories every physiologic study we've ever done says it goes down and you know it must go down so for example if you take somebody who's uh 200 pounds you say you cut 500 calories a um you know a day you lose a pound a week does that mean in 200 weeks they'll lose the weight zero pounds like no absolutely not that will never happen even if you stick to 1500 calories so therefore your metabolic rate

must go down at some point turns out it goes down almost immediately and persists so therefore this idea that it was all because they skipped on their diet right that that's not true it might have just been a very poorly constructed diet that is not taking into account just the foods but also the sort of eating duration the fasting the hormones what hormones you're stimulating with the foods that you're eating what information you're giving your body what instructions you're giving by there's so much of that other other things that are important yeah um yeah and

i think it's time to take that sort of guilt and shame away from those people we're all sort of working together yeah it's a great point let's get to um the sort of practicalities you've mentioned in your books you mentioned this conversation that chronically elevated insulin is problematic for a whole variety of different reasons yes for the developments of type 2 diabetes so putting on weights also you know a lot of people aren't aware that it increases blood pressure increases fluid retention increases uh a type of cholesterol called vldl very low density lipoprotein which can

be problematic and so for a variety of reasons we want to lower that so there's two broad ways i'm getting that we can do that one is through a diet that does not constantly push up insulin and the other way is with a form of intermittent fasting or you know bringing in some type so if we if we start off with food and diet you mentioned low carb early on in this conversation of course we know how divisive um the diet landscape currently is in your experience if we're thinking about a diet food choices that

don't spike insulin too much what are the kind of principles you like your patients to follow yeah and i think this is where um you know there's always a lot of difference in opinion there's low carb versus high carb and i actually think that there's a huge difference even within carbohydrates so the the problem is not generally the carbohydrates but the processing that makes the biggest difference so if you look at the glycemic index which is um you know which looks at carbohydrate containing foods sees how much insulin tends to go up and glucose tends

to go up they tend to go up together of certain foods what you see is that unprocessed carbohydrates tend to cause a lot lower spike in insulin than than processed foods you take cereals like cheerios and stuff they're really really high you take a very refined product like white bread uh just very very high then you look at something like boiled potatoes and it's just extremely low they're both carbohydrate-containing foods um so there's a big difference even within carbohydrates beans beans are carbohydrates they have a different type of amylopectin they have amylopectin c versus amylopectin

a their digestion is completely different they're still carbs so trying to simplify it to just carbs is difficult because you could eat a lot of beans and who gets fat eating beans like very few people are you talking about like black beans kidney beans these sort of things yeah the type of carbohydrate they contain is amylopectin c which is harder to digest and therefore leads to much lower blood glucose levels much lower insulin levels but insulin is sort of that key so even within carbohydrates so so people think well one of the things is to

cut carbs which is just a reasonable thing but cutting the refined carbs does a lot better because you have to understand that a lot of countries a lot of cultures have had high carbohydrate intakes and in the past have never had a big problem so china for example was classic in the 80s it was eating 300 grams a day of carbohydrates almost all white rice and there's almost no obesity this is 1980. then of course recently they they started eating a lot more processed foods a lot more sugary foods now their obesity is just exploding

but it was not just the carbs why this is really interesting for me so white rice is a refined carbohydrate why do we have societies with high volumes of carbohydrates who are not putting on weights and who are not getting type 2 diabetes and that example use of china that's really interesting 300 grams of white rice a day you would think would spike insulin and would um you know cause people to get sick but it wasn't and it wasn't and what if you know one of the theories i put forward in my first what was

this idea that maybe in the west in the the modern world in which we now live where people are chronically stressed they're chronically underslept they're chronically under active and they're eating a lot of highly processed foods all together that's creating the perfect conditions for high levels of insulin resistance and i thought well maybe the low carb diet has a particular utility in modern stressed out cultures i i don't know have you got any comments on that and how do you explain that in the 1970s they were eating this in china and not getting sick i

think there's a few things one is that the amount of sugar they were eating was just almost zero yeah so sugar which is fructose is metabolized quite differently than glucose so when you metabolize glucose all your cells in the body can use glucose when you metabolize fructose only the liver can use fructose so the fructose goes straight to your liver and there it gets converted and causes fatty liver causes all kinds of things when you're eating too much fructose so it can get converted back into glucose but for a lot of reasons it just gets

turned into fat through de novo lipogenesis you get fatty liver you get insulin resistance which causes hyperinsulinemia so the fructose is actually much worse for you than the glucose in my opinion because you know if you are 150 pounds you have 150 pounds of body that's using glucose versus sort of five pounds of liver that can metabolize fructose so the fructose is much much more obesogenic i think than the uh glucose so therefore the practical side is that sugar and sweet things like that are just much more fattening than starchy foods so maybe you're saying

then in china back then because they're not having much fructose yeah almost zero but therefore they can actually the bodies can handle the 300 grams of white rice each day whereas on the background if a lot of fructose which which is of course how many of us live these days too much sugar too much fruit juice all these kind of things maybe with a background of that suddenly the white rice starts to become problematic uh yeah i think so i think the fructose uh really makes that that much worse but the other thing is um

that there's different reasons why and two they weren't eating all the time right they weren't eating constantly it's not like they're eating eight times a day of white rice and the third thing i think that's sort of always overlooked because it doesn't fit into this neat little square is that there's different reasons why we eat like there's the hunger the nutrition part of thinking which we think is important but in this day and age it's probably the least important of the reasons that we eat there's the habits right you eat because it's time to eat

that's really the only reason and you eat because it's delicious so if you take any diet that is monotonous so no matter what diet it is so you can eat say say you love pizza but i give you pizza breakfast lunch and dinner okay very soon much sooner than you think you are going to be so sick of pizza that if i continue to feed you pizza you're just gonna say okay i'm gonna eat as little of this pizza as i possibly can until i'm no longer hungry because i just don't like to eat it

it's the same thing with white rice if you eat white rice and vegetables every single day three meals a day which is you know what they're eating in china like different types of you know vegetables with white rice pretty soon you're going to be like i will eat the rice because i'm hungry as soon as i stop being hungry i am stopping eating because i know the hedonic effect of food the pleasure giving sense of food goes away when it's it's completely monotonous so you can eat all that and you know you're not going to

overeat it because you don't want to you just want to make sure you're not hungry and therefore any monotonous diet always works because you've just very quickly run out of things that you want to eat yeah so what we've done of course in the modern age is we've introduced all kinds of varieties of food which keeps us eating beyond these we're full sort of stage i've got my nutrition i'm done i don't want to eat anymore we never get that state because we're always like well you know we want to keep eating and then you

get around it by snacking because even if there's lots of good things to eat so you go to a buffet you know all you can eat restaurant you know after a certain point you have to stop like you can't keep going it's you know if you've eaten everything and somebody says hey why don't you have a bit more of this pork chop you'd be like oh that's going to make me throw up right it's the same pork chop as you ate like 20 minutes ago but you're now full so the point is that if you

if you take away the sort of pleasure giving part of food then you're going to be able to control a lot of overweight obesity which is what the right rice was right it was monotonous it was just every single day was the same thing like i i can tell you i i i ate rice a lot growing up because my my parents were immigrants they came from from hong kong we ate rice probably every single day so yeah i like rice all right but you know until you're full then that's it like yeah you know

i i don't want to eat more than i have to because i've eaten too much of it already so so that's why it's always you know people say oh therefore carbs are good or you have the kempner rice diet from the 40s hey that proves that carbs aren't the enemy it's like no no no it's very complicated like you can't just simplify things into like this food is good and this food is bad right so there's a lot that goes into sort of understanding it and satiety plays a big role in that that is why

the things that are most successful at controlling weight are hormonal agents that control your appetite so nicotine is a classic example it actually suppresses your appetite people notice this when they stop smoking that their appetite goes up and it's probably because it was chronically suppressed same thing the cemaglotide the drugs that some of the drugs that are used now but anyway so so it means that the carbohydrates are not the only thing that matters it matters um the type of carbohydrate so is it amylopectin a ammo vitamin c how often you're eating it because it's

not just how high you spike it and how refined it is going to affect how high it spikes the foods you eat it with are also going to make a difference and this is always very interesting to me because you can take the same foods and you're that's not what's important the hormonal response is what's important if you take the same food at breakfast versus dinner you're gonna have a different insulin response to it so you're gonna actually have a much higher insulin response at nighttime versus breakfast same thing with something like vinegar and this

is very interesting actually i think so when you take sushi rice for example which is vinegared rice um when you take an acid or lemon juice with bread or vinegar with bread for example you can take say 100 grams of bread and you can measure how much your glycemic index goes up and when you take it with the acid it's like 50 60 of what it was without the acid which is fascinating because of the same 100 grams of carbohydrate so say you take white rice versus vinegared rice the glucose level and the insulin level

goes up to about 65 69 something like that versus 100 so you have much less effect and there's an interesting reason why that is and it's because there's in terms of digestion of starch is suggested by a hormone called amylase there's salivary amylase and there's pancreatic amylase so the assumption so you eat bread the saliva contains amylase starts breaking down that starch because remember starch is a chain of glucose you need to break it into little pieces so that you can absorb it the saliva contains amylase that immediately starts to work it and we had

assumed always that most of the digestion is through the pancreas it turns out that up to eighty percent sixty to eighty percent of the digestion can be salivary amylase because salivary amylase is deactivated by low stomach ph so we assume you chew it boom it goes into the stomach and all of a sudden salivary amylase stops it stops breaking down the starch but in fact because of the bolus of food the ph of the stomach actually never gets down there and that doesn't get low enough to deactivate salivary amylase so if you take something like

bread with vinegar like they do you know olive oil and vinegar for example it turns out that you're you don't break down the same amount of starch and therefore your glycemic index goes uh much lower your insulin spikes go much lower and it's because of the acid in the food the lemon juice does that fermented food does that which is lactic acid vinegar which is acetic acid does that so there are things that you can take with the carbs that will also affect it if you take carbs first versus last in the meal if you

take it with protein or with fat it's going to make a difference so there's so many things that make a difference other than just cutting the total number yeah i love that and i think that officially qualifies as a hack you know the term hack is you know thrown around a lot these days but that seems like a really practical thing that people can do within the context of their own diet just to lower that glucose and lower that insulin response in the body the other thing of course i can do is think about the

food order and i know you released a video recently on your youtube channel about this why is the order in which we eat foods important when we're thinking about glucose and insulin yeah and it's again it was the same sort of thing where they did a study where they had people they ate carbs first and then waited 10 minutes then had their fat and protein versus taking the fat and protein then waiting 10 minutes and then eating the carbs and again same number of carbs same type of carbs right same food same amount of food

in the carbs exactly yet the rise in the insulin was like 50 of what it was and remember the insulin is what's telling your body to hey store this this energy store these calories away so if the less of this insulin you have trying to store it away the more you're going to leave out in the body for you to use this energy and it's going to keep you fuller longer so that's that's the the food order so basically the whole hack would be just shift your carbohydrate intake to the last part of the meal

instead of the first part of the meal and that's going to do two things one it's going to make you less wanting to eat the carbs because you're already full from the fat and protein and two the amount of carbs that you take even if it's the same is going to have less of an effect on you so it's it's it's so so you know this is what i mean when i say it's a complicated topic and people who try and simplify it to total calories or total carbs always wind up missing a few things

because there are ways to get around it because you know we have eaten carbs in the past without without gross you know worldwide obesity epidemics right yeah this is something i've i've done for a good couple of years now and more recently with the kids my kids are 12 and 9 at the moment and i will if i'm cooking dinner i will serve them their protein source and their vegetables first and when that's finished or almost finished then i'll put on i don't know the sweet potato mash or whatever else you know whatever whole food

carb we're serving with it and you know because it's very hard for me as a parent knowing the science knowing the impact not to try and implement it because it's pretty straightforward to do actually and it's something that i think anyone listening to this or watching this right now can can experiment with themselves you know eat the carbs last and you know there's there's a really good video on your youtube channel that i think will help people understand the science of that as well um jason moving to fasting intermittent fasting what if someone's kind of

heard what you've had to say so far and saying okay all right um i'm interested in trying intermittent fasting where would you encourage them to start and before you answer i also want to say one of the things i think is so great about the practice of intimacy and fasting is that it doesn't really matter what dietary tribe you belong to you can still practice this and get benefits right so i think it cuts through straight away through all that noise um so yeah maybe maybe some tips for people on on where they might want

to yeah i think that the first place to start really is just to go back to sort of uh you know eight hours 10 hours of eating sort of thing um if you want to eat sort of breakfast at eight nine o'clock in the morning and finish by like six o'clock in the evening and then let the rest of the time be fasting you know you're talking about a eight nine ten hour or eating window it may be 14 to 16 hours and that's relatively easy to do and of course it's something that people have

done for for many many years so cutting out the snacks cutting out the late night eating and then you know so if you cut out the eating after dinner and push your breakfast a little bit later then then you're automatically going to get that that period of time and that's a great place to start and then you can experiment you can go longer or shorter depending on what you like um but i think that's that's probably a good place to start off with that's going to be safe for everybody um you know there's no there's

no problems with with anything you're still going to be eating and relatively normal um you know meal schedule and so on but you know there's so many or there used to be at least so many sort of uh myths about fasting about how it was so damaging to you and all this i think you know it's important to get that right information as well people used to think oh well you know it's it's gonna burn muscle and it's like you hear this all the time and i'm always like okay if you're an elite athlete sure

maybe maybe that's something you have to be mindful of but for most people who are not elite athletes um you're just sort of regular people you know this idea that it's going to burn muscle is still very much ingrained you see it out there lots of people talk about it and it's like do you really think that our body is just so stupid that we would store calories as glucose and body fat at the minute that you don't eat anything you're gonna burn muscle like you think that we survived as a species to become the

dominant species on earth because our body is so intrinsically stupid like it's sort of like storing firewood you know for the winter and then as soon as it gets a little cold you chop up your sofa and throw it in the fire like what like what like why are you storing body fat if you plan to use that that that muscle it's like ridiculous and i think it's a it's a huge misunderstanding of the physiology so i have a video about the five stages of fasting and there's a period of time in there that actually

is called gluconeogenesis so when you think about the physiology of fasting there's a lot of good things that happen but essentially your body goes from eating food then it starts using glycogen which is sugar it's it's basically chains of glucose that are stored in your liver and then after glycogen then there's a short period of gluconeogenesis which is protein and that's where people say wow that's your that's where you're breaking down muscle you have to say no protein is not the same as muscle protein is a lot of things there's lots of excess protein on

our bodies skin for example is protein connective tissue the thing that binds it all together is protein when you break down proteins your body is going to break it down and then rebuild whatever it is that you need so if you need muscle you will build it if you don't need it you won't build it like the only thing that builds muscle what what builds muscle and loses muscle is not how much or how little you eat or protein you eat it's the exercise that you do like i'd love it if i could eat and

build muscle but i don't like it doesn't happen ever as much as i wanted to and it's the same thing when you're breaking down protein it's not necessarily muscle if you're using the muscle it's not going to get broken down but what you are going to do is break down the skin the connective tissue the stuff that you don't need and this is this process called autophagy where your body is actually going to break down organelles in the body because it's not necessary and it's a process of cleaning out the unnecessary stuff so people who

did intermittent fasting we have people lose you know 100 150 pounds they haven't sent anybody for um skin removal surgery because that was protein that was removed not fat and that's all anecdotal i know it's not sort of proof but we have a lot of people who say well my skin has tightened up too it's like you don't get that with just body fat loss that's protein loss sorry synthetics if you are enjoying this content there's loads more just like it on my channel so please do take a moment to press subscribe hit the notification

bell and now back to the conversation if you if you look at the amount of protein on the human body in somebody who's overweight it's it's far in excess they have more protein than somebody who's who weighs less it's not just the fat it's all the stuff that helps to support the fat that the blood vessels the skin the connective tissue right and that all also has to go with that so yes there is a period of breaking down proteins during the period of fasting sort of around 18 to 24 to 30 hours something like

that but it's not necessarily a bad thing it doesn't mean your body is breaking down muscle you will lose muscle when you don't use muscle so you're saying start off for people maybe a 10 hour eating window as you say let's say 8 am till 6 pm is your eating window out with that what's in your view because you take a lot of people through these fasting programs i know in your clinic what are they permitted to do outside the eating window in terms of drinks and other things that's the first question and then going

beyond that it's like what benefits then might people once they start there and go okay this is pretty easy i can do that i'm feeling better lost a bit of weight i'm sleeping better i feel lighter what are the benefits or why should some people consider going further because i think in your clinic am i right in saying that sometimes you take people into 36 hour fast 48 hour fast those sort of things so maybe just yeah just just just walk us through that if you if you will yeah so you know classic fast is

water only but really you don't have to be that strict there's no rules like uh you know when you're talking about fast and there's two main variables one is the length of fast and two is what is allowed during that fast and you can put you there's lots of things so tea for example is something that i recommend for a lot of people um you can drink coffee and then those really don't have too much effect on you know your body there's no calories and you know green tea and uh it really doesn't have much

effect on the other hand the coffee and stuff it's gonna have the coffee and tea they both have things like stimulants like caffeine and that may keep your sort of energy uh you know your your metabolic rate a little bit higher so yeah maybe there's a little benefit from those although the effect is relatively small so teas coffees herbal teas those are all great to do then you get into things that are more clearly food so things like bone broth for example and then people even take like small salads and stuff within that fasting window

you know if they get very hungry for example and those are you know people think well you know i just broke my fast right i have to start all over that's not what happens because what happens is that when you're fasting you're trying to force that insulin level down so if your insulin level is going down your body is going to switch towards using your your your stored calories not not the food if you break that fast with say you know oh i had you know some bone broth yeah your insulin's gonna blip up for

a little bit but it's a very small amount and then it's just gonna start going back down again it's not gonna have a huge effect so even if you take something during that fasting window it doesn't mean that all of your progress has been lost you have to start from scratch again so you don't have to worry so much but generally i tend to tell people you know just stick with like cheese coffee if you put a little bit of cream in the coffee because that's what you're used to go ahead it's not going to

make a huge difference but don't put like the whole you know carton of cream in it then then you're talking about food more than anything else and then the other thing is in terms of the benefits of fasting why continue with it um there's a lot of reasons like if you think about the physiology of what happens during fasting there's a lot of good things that happen people always assume that they're gonna be tired uh during fasting but that's not actually what happens so if you if you if you don't eat there's a very sort

of stereotyped response that is insulin is going to go down but certain other hormones are going to go up and one of those hormones is the sympathetic nervous system and growth hormone so both of those go up as you fast sympathetic nervous system is part of this sort of parasympathetic is sort of relaxing sympathetic is sort of stimulating it's a sort of fight or flight response so it's it's it's uh the hormones involved they're mostly noradrenaline and adrenaline so you actually activate the sympathetic nervous system when you don't eat and this is sort of basic

first-year medical school stuff it's it's it's a number of hormones called the counter regulatory hormones you get a spike of this counter regulatory hormone in the morning um around 5 a.m 4 a.m 5 a.m and it sets you up for the day it's pushing the sh the the the calories the energy but into the system so that you have energy for the day ahead so that's why you don't necessarily have to eat the minute that you get up because your body's already started fueling yourself from its stores and because you're having higher levels of sympathetic

nervous system you're going to be able to concentrate better you're going to have more energy as you fast not less energy like think about it uh you know if you have a lion who just ate it's sort of sleepy just wants to lie there and digest but you have a hungry wolf is it sort of like falling over because it can't concentrate no the hunger is what makes it dangerous because it's dialed in it's concentrated and it's got energy to burn it's just getting its energy from its stores not from its food and that's because

that you and it you know again it's not some voodoo magic psychology it's just physiology your body is ramping up at the time that you're fasting well that's great you're gonna have more energy i've had people come in you know women and their husbands would be like i can't keep up with her anymore like she walks so fast i can't even i have to tell her to slow down and she's like you know it's because i have so much energy it's like yeah because now you're releasing that energy you've now finally allowed your body to

access the stores of energy by allowing insulin to fall by fasting you're allowing your body to access this huge store of calories this 100 000 calories that you've had stored away that you've never been able to access before because insulin is always blocking you now you have access to this energy they're like well okay let's use it let's use it your body's pumping up the sympathetic tone some people actually can't sleep because because they're so pumped up when they're fasting but then they can focus better we know that people you know in terms of their

mental abilities are do better with fasting so it's a fascinating process but a lot of good stuff there it's it's just crazy how many people have never ever experienced anything like that because of what we were talking about right at the start of this conversation where you know over 50 of the u.s population who don't work in shifts are consuming foods over 15 hours a day so they're nowhere near able to actually experience these things that you're talking about and i think another thing which i often think about with fasting is that humans have been

fasting for donkeys years right if it was dangerous how would we possibly have survived this far now on that i think a couple of caveats and i know you deal with a lot of patients with type 2 diabetes do people in your opinion need to be careful if they are taking blood sugar lowering medications or injecting insulin i think we should just sort of briefly mention that in case people jump straight in yeah absolutely so remember that when you're um fasting and your body is going to be using glucose stored glucose whether it's in your

blood or whether it's in your liver if you're taking a medication in addition to lower your blood glucose you could possibly go too low and yes it could be very very dangerous so you if you're on medications you should always speak to your doctor but for a long time people used to say well that's why type 2 diabetics can't fast it's like no that's why you have to be careful because the thing about the fasting is that it is a way to help lower your blood glucose if you're lowering it with fasting and you're taking

your medication then you'll go too low but it doesn't mean that you should not fast it means you need to take less medication it means you're over medicated so you need to adjust that medication not that the fasting was wrong because the you know this is a natural way to lower your blood glucose like what could be better than that yeah but we don't see that as doctors do we you know it's like no it's it's a given that you stay on the medication oh no this is dangerous or adding in fasting it's like well

hold on a minute it's just you can think of it as a third medication and just think oh if i'm going to add this one and maybe i need to take this one down or take this one off but it's not it speaks to this wider problem that we don't as a profession in my view give things like fasting or changes in food quality the same priority the same level of importance as you know tinkering this medication by 10 milligrams here do you know what i mean it's kind of like no absolutely and it's it's

very frustrating it is because um for example you'll have um if somebody is on insulin for example and their blood glucose goes down so what is the advice that we as a profession give well eat something right it's like okay well sure at that one specific time yes i agree but in general if you're going down it means you're over medicated because i'm giving you this insulin to get your sugars low and your sugars are going too low so you're over medicated so you need to reduce the dose but we don't think that way because

we think okay well what you should do and this is i i've heard actually dietitians say this all the time you need to eat to cover your insulin it's like what so if you take insulin your sugars go low then you eat what do you think is going to happen you're going to gain weight if you gain weight what happens to your type 2 diabetes it gets worse why don't you instead not eat take less insulin and then you're going to lose weight as you lose weight your type 2 diabetes will get better but you're

absolutely right like we've gone in the wrong direction thinking that the the medications are what's good for us and everything else has to fit around that and it's it's part of the problem is medical education because again i've gone to so many meetings and these are given by the heads of you know diabetes associations and stuff right and they'll go okay the number one two and three uh treatments for type 2 diabetes is you know diet diet diet right okay great then they spend the next 59 minutes out of that 60 minute lecture telling you

about drugs so the message to all the doctors these are training doctors and established doctors is that yes we will give you lip service about diet and lifestyle but what we're really here to talk about is meds right and that's wrong that's absolutely wrong thing because think about this simplistically right type 2 diabetes is largely a dietary disease and we're using drugs to control a dietary disease well you're not going to get as much effect as you think you will because you're not focused on the root cause which is the diet yeah this is such

an important point when when i teach doctors on this prescribing lifestyle medicine course a lot of doctors will say initially that old patients don't do what i tell them to do you know and i often give the example of a 10 minute or a 15 minute consultation with a patient in general practice where they've just been diagnosed with type 2 diabetes and we do a role play on stage i basically try and demonstrate two different consultations one where basically you spend the first nine of those 10 minutes or 14 out of those 15 minutes talking

about medication and the fact that this will stabilize your blood sugar you're probably going to need another medication in the next year and within a few years you're going to be on insulin and then as they're walking out you say oh if you could lose a bit of weight and move a bit more it's going to help you and then we do another one where actually you spend the first 90 of that consultation helping them understand what's caused it giving them help as to how they might change their lifestyle all these kind of things and

then you also mentioned that there may be some medications and you ask the question to the doctors well what message is that patient going to get if you spend 90 percent of the time on lifestyle and 10 on medication versus the opposite what's going to happen of course the patient's going to go out with the impression yeah he mentioned diet at the end but really it was all about these medications but it is starting to change that that is for sure maybe not fast enough for people you mentioned women before and a woman who was

full of energy and her husband wasn't able to keep up there's another kind of maybe a myth about fasting which is that it suits men better than women have you heard that myth and what has your experience been with that yeah i've heard this myth before that women shouldn't fast or they can't fast or they don't get results from fasting and it's really i think just not true like not all men do well like there's lots of men who don't do well you just don't hear about them um the women can fast like there's nothing

inherently dangerous about fasting in women they do probably respond a little bit differently like men tend to some men lose a lot of weight like right up front like very very quickly like you know sort of like 60 pounds and like you know a month sort of thing like really really fast and uh where whereas women do tend to be sort of like more slower and stable and i think some of it is just the sort of baseline like some men really just like their diets are just really like they're obviously not good like they're

just eating out fast food like 100 of their meals sort of thing right so it's just such a horrific baseline uh of processed food that as soon as you change that like and you don't see that with women women are tend to be a lot more diet conscious um so then you don't get people who have those horrific baselines of mcdonald's for every meal sort of thing whereas you do that you do see that with men like with men you you get that and therefore you know as soon as you change them to sort of

like whole foods their weight just undergoes these dramatic changes so i think that it's you know not just the fasting but it's the foods as well right so there's two components right there's the foods that you eat and then there's the time that you're not eating and i think it's it's yes there probably are some differences with men and women like people talk about sex hormones you know menopause for example and i think that there is definitely something there like the sex hormones do play a role in how much fat you you gain and lose

it's just a fact and this is another part of this whole calories thing that i always find incredibly like i don't understand how any serious scientist can think about calories is the only thing because think about adolescent girls and boys okay so pre-puberty girls and boys are roughly the same sort of weight and body fat and so on then you go through puberty and women in general are have about 50 more fat than boys it's not that they have less willpower like obviously not the difference was that the boys had a bunch of testosterone they

gained more muscle whereas women tend to develop fat in their hips and their breasts right it's it's just that physiology that's the difference between exposing somebody to a lot of estrogen versus testosterone but it's not a willpower problem it's not a problem with their diets necessarily right so so it's not like you know and this is you know people who say well you know it's all about willpower it's like well then you must think that women have less willpower than men it's like that that that's not true like it's not true in any sense so

therefore it's sex hormones that play a huge role women do have a difference in sex hormones and during menopause so we know that there's a certain number of changes and that may play a role in weight loss but there's nothing you can do about it like i i'm not gonna they're menopause so therefore you just have to deal with it so does it mean they can't fast no it doesn't mean they may respond differently than men yes absolutely they may take a little bit more time because their bodies had been programmed were programmed by nature

to carry more fat that's not their fault or anything necessarily bad it's just physiology that's the hormones uh speaking and i think you know all these things are very individual right some things work well and quickly for some people some things don't that's it's kind of the way it is and then also we have to be careful about how we're measuring the impact i mean if weight loss is the only metric people are looking at they may think that intermittent fasting potentially has failed for them but actually the benefits as we've touched on on multiple

occasions throughout this conversation go far beyond just weight so there are there are implications for your gut function often i've found people with ibs type synthesis it really clears up massively when they have periods of fasting sleep can improve you know all kinds of things other things can benefit so you know i definitely encourage people to experiment and see the other thing jason often comes up with fasting particularly these days is the issue of eating disorders which as you know are rampants they're on the rise particularly in adolescents you release a video on this recently

i saw on your youtube channel which i found really really interesting what is your view on whether intermittent fasting whether me and you having a conversation like this is toxic for people who may be suffering with eating disorders i mean what is your view on that yeah and and this the literature really says that there is not a lot of um danger with that so when we're talking eating disorders generally we're talking about anorexia nervosa and bulimia those are the two big sort of eating disorders so they've done studies um where they've basically looked at

it so they take people not you know there's there's two two main concerns right with dieting or fasting and eating disorders one is that you're going to be so hungry that you're going to trigger like overeating or binge eating and two is that there's maybe you don't take enough you know amino acids and tryptophan therefore you're going to get a little bit depressed and then therefore you're going to overeat but neither of those possibilities turned out to be true so in the studies what they did was there's one study where they looked at this where

they had people they fasted them and then said you know what are your levels of hunger do you over eat and so on and and the bottom line was that people tend to eat a bit more than meal after a fast and this is a 24 hour fast but if you look at the full 24 hours they're still not eating nearly as much as they used to and then two was that they did you know they took people with diagnosed anorexia and bulimia this was a separate study and they they again put them through fasting

and they they were basically wanted to see if this was going to trigger their eating disorder and again the conclusion from that study was that it did not so it sounds like it's a plausible concern and you know i don't want to minimize it because eating disorders is a very serious problem of course um but the available data so far hasn't um hasn't really borne out the danger that it does like it doesn't suggest that there is any danger from that you know i want to just be careful because there's just not a lot of

research into that and i always want to be careful because you know fasting is a tool and tools always they can help or they can hurt it's not the tool it's how you use that tool so if you use you know a blade you can cut out a tumor for example you can cure somebody but you can also kill somebody so yeah if you're talking about intermittent fasting like in you know somebody you know you have a 16 year old girl who weighs like next to nothing with a bmi of 15 no you do not

want to be talking about it but you have a 60 year old man with type 2 diabetes who weighs sort of like you know has a body mass index of 45. well then yes absolutely you want to be talking about it but it's the skill of the person using it so you know you have to choose your situation like to say that fasting is bad for everybody well that 60 year old man who's you know super super you know morbidly obese his risk of anorexia nervosa is almost zero like there's no reason not to talk

about it with him the risk of a 16 year old girl who weighs almost nothing and has a bmi of 16 yes her risk is extremely high you should not be talking about that with her so you know it's it's it's it's not the knife it's the way you use that knife fasting is exactly the same yeah it's a great point hba1c is a common blood marker that many people get done at their doctors which is a you know an average measurement of our blood sugar over the past two or three months with all your

experience of course if it hits a certain point we call that type 2 diabetes if it hits a slightly lower point we call it pre-diabetes do you have a sense these days of what an optimal level might look like for someone i i understand that you deal with a lot of type 2 diabetics in your kidney clinic and you help them put their type 2 diabetes into remission certainly get that a lot better using the things that we're speaking about but i but i i've often thought in medicine that we it's very black and white

you either have pre-diabetes and type 2 diabetes or you're normal but clearly that's not the case this is a progression that at some point you flip into pre-diabetes and at some points you flip into the type 2 diabetes diagnosis so do you have a sense of what an optimal level might look like for someone who's trying to safeguard their health for the future um if you look at studies really the lower the better um and i think that those definitions are mostly because um the the whole um the whole thing is that you have to

have definitions to do studies so you need to classify so 6.4 is not that big but 6.5 is that like the difference is very small but at some point you have to draw that line and it's it's an artifact of um doing studies so you have to classify people because you can't just say 6.1 6.2 so you can't have like you know 15 different categories in the study it'd be really confusing so so you break it up and you say okay well at 6.5 you're this and 6.0 to 6.4 is this and less than that

but it's really a continuum so there's no real best number in clinical practice though i've seen a lot of people um who are like 5.9 6.0 and they seem to do fine what i think is important from an individual basis too is not just the level but also the stability of that level over time so i've actually seen a number of people and i always thought this was wow you're like almost pre-diabetic or you're pre-diabetic but they actually just trundle along just fine and they're always at 6.0 and i think that that's another thing that

i'm not sure is captured with the actual number is sort of if they've been like this for this many years is it really bad or is it not i actually thought this because it was a relative of mine who i tracked relatively closely for like 20 years and it was like 6.1 6.0 6.1 6.0 and they did fine they'd actually never had any problems whatsoever and i thought i wonder if it's just like their diet didn't change their weight and change and they're pretty healthy uh throughout but i just always wondered is it really bad

or is it that person who goes from 5.3 to 5.5 to 5.7 of 6.0 to 6.2 maybe that's what's bad so i think you know there's two things one is the actual level and two is if it's at a sort of borderline level is it going up or is it sort of stable because what's really going to be bad of course is when it goes up over uh 6.5 then clearly you're in the abnormal right that's super interesting i suspect over the next few years we'll get a lot more clarity on this as science in

this area progresses um jason had we had more time i was wanting to get into your latest book the cancer code which is just brilliant maybe i can tempt you with a part two at some point in the future because i think the way you've articulated your thoughts on cancer and how our understanding of it is developing is pretty profound and it's a brilliant read for anyone to finish off this conversation we've covered a lot so far this podcast is called feel better live more when we feel better in ourselves we get more out of

life right at the end now jason in all your years of experience yes in clinic but also you know spreading information on the web through your books what are some of your very best tips for people who have heard what you had to say go right i'm in i want to make some changes i want to start looking after my health i want to start lowering my insulin what practical advice have you for them right at the end here um i think that the the most important thing i think is to focus on sort of

foods and less on nutrients like carbs or you know that kind of thing focus on the sort of eating whole foods is still probably the most important thing whether it's a carb or whether it's not i think that's still probably the biggest thing we don't talk about it as much as we probably should right in the whole uh thing about carbs and you know keto and this diet and that diet it all winds up and you know vegetarianism and that's it always comes back to eating sort of natural foods and eating in a way that's

not constantly stimulating so you know to me it's it's relatively simple and not that controversial one don't eat too much sugar i don't think that's very controversial to try to eat unprocessed foods which i again i don't think is all that controversial and three don't eat all the time like if you're overweight don't eat all the time like cut out those snacks which i you know to me just seems like hey this is just what it was in the 1970s like there was none of this count your carbs count your calories count discount that eat

whole unprocessed foods whether it's you know vegetables or even meats enjoy your foods when you do eat them but don't eat constantly give your body a break once in a while from eating so that you can digest your foods like that's all your grandmother ever wanted to tell you like give your body a chance to digest the food that you ate don't just keep shoveling it in you got to use it because when you're putting it in it's got to come out at some point otherwise you're going to get into problems so those three things

i think are sort of still the core of everything without getting too complicated don't eat too much sugar you know eat unprocessed foods and don't eat all the time great advice to finish off jason want to acknowledge you doing fantastic work you're helping so many people i think your books are fantastic which books would you drive people to and where else can people stay in touch with you if they want to keep up to date with your work yeah so i think the best place to start is the obesity code it sort of goes into

the science of weight gain and weight loss i have a number of youtube videos now which sort of covers a lot of that material in sort of less than 10 minute chunks so i think that's that's what i've been doing sort of the last year to to sort of help spread the message and um the other the other ones you know you can also follow me on twitter uh at dr jason fung and then uh you know but but the cancer code just to address that i actually think is the most interesting attempt to me

it was the most new information uh about cancer but not it it doesn't follow along with diets and insulin and so on quite as much as the others it's more of an exploration of sort of what this disease is to me that which is a you know and actually a really fascinating uh story but it's not it's not going to change in terms of what you do with the medicines that you do it's not a diet it's not completely a dietary disease so therefore it's not a dietary solution as opposed to say the the obesity

and diet type 2 diabetes which are dietary diseases so the obesity code the diabetes code are both uh there to you know just for you to get more information about that yeah thanks jason that's your work and uh hopefully get you back on at some point in the future if you enjoyed that conversation i think you are really going to enjoy this one with a brilliant cardiologist who uses fasting to help his patients i've been a cardiologist for 30 years and i've tried everything but when i tried fasting i started seeing changes people began to

lose weight people's blood pressures came down diabetes got reversed