[Transcript] – The Complete Guide to Fasting: How To Heal Your Body Through Intermittent, Alternate-Day, and Extended Fasting

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Podcast from:  https://bengreenfieldfitness.com/2017/06/the-complete-guide-to-fasting-how-to-heal-your-body-through-intermittent-alternate-day-and-extended-fasting/

[00:00] Introduction/Ample & TeloYears

[05:14] About Dr. Jason Fung

[08:26] Circadian Rhythms & Fasting

[16:01] What Happens When We Fast?

[21:42] Phases of Fasting

[27:11] Fasting & Growth Hormones

[40:56] MarcPro/Hello Fresh

[44:34] On Skipping Meals

[56:34] On Extended Fasting

[1:02:40] Refeeding Syndrome

[1:07:30] World Record for Fasting

[1:14:11] End of the Podcast

Ben:  Well, this is awkward because I'm about to tell you everything that you need to know about fasting.  This is Fasting 101, and far beyond.  It's an interview with the author of what I would consider to be the most complete guide to fasting that's out there, and the reason this is awkward is because before we talk about fasting, I have to tell you about something very tasty that I had for breakfast.  I took one bottle of this stuff, and I dumped it into a blender with ice, with half an avocado, with a few teaspoons of cinnamon and with some sea salt just 'cause I like to add a little bit of flavor.  I blend it all up for about two minutes, and something about the salt and the ice being blended for a long period of time makes this stuff taste like freaking chocolate ice cream.  It's got fats from coconut oil and macadamia nut oil.  It's got fiber prebiotics, probiotics, a ton of different probiotic strains, seven to be exact.  It's soy-free, gluten-free, GMO-free, no artificial flavors, it's a BPA-free bottle.  It even comes in a 400 calorie and a 600 calorie size.

It is one of the most unique meal replacement blends I have ever gotten my paws on.  I even interviewed the meal founder on my podcast.  This guy's name is Connor Young.  It's an amazing food.  It's called Ample, A-M-P-L-E.  You can get your hands on this stuff if you go to amplemeal.com.  That's amplemeal.com.  He's giving everybody a 15% discount, and you just use code “Greenfield” to get a 15% discount.  That works on everything except their lifetime supply, which is actually a pretty cool idea to get a lifetime supply of this, but otherwise, just use code “Greenfield”.  You don't have to mix it with ice.  You can just add water, shake it up, and drink it as I have been known to do on airplanes when I don't want their microwaved egg powder.  So check it out, amplemeal.com, and use code “Greenfield” to save 15% off.

This podcast is also brought to you by something that is enhanced quite a bit by calorie restriction and fasting which you're about to learn all about, and that is your longevity.  There is a way that you can test via a very simple and actionable DNA evaluation, the telomere length of your cells.  Meaning, these are the protective DNA caps on the ends of your chromosomes.  They tend to shorten with age, but you can change that, and you can actually decrease the rate at which your telomeres shorten when you do that, your biological age winds up being younger than your chronological age, and you can track all this.  You can quantify all of it via a very, very simple blood test.  I've done it, and the way that you can do it is you go to this company called TeloYears.  They're giving every one of my listeners 10% off of this longevity evaluation.

You go to bengreenfieldfitness.com/teloyears.  That's bengreenfieldfitness.com/TELOyears, and the discount code you want to use is “Ben 10”.  That code is valid through August 31st of 2017, use code “Ben 10” to get 10% off this TeloYears kit, and you too can find out if you're getting older way freaking faster than you should.  Or if you're not, and you're getting younger,  you can find out whether anything, supplements, food, exercise, whatever is affecting you negatively, positively when it comes to aging.  So check it out, bengreenfieldfitness.com/teloyears, and use code “Ben 10”.  Alright, let's go talk about not eating.

In this episode of The Ben Greenfield Fitness Show:

“If you are a hunter or a caveman and you don't eat for a couple of days, your body starts to shut down.  You will never eat again.  You have no energy to go out and hunt.  You have no energy to catch those rabbits, whatever.  So your body simply isn't that stupid.  What it does is it switches energy sources.”  “Once you start to fast where you just don't do anything at all, you start to see little spikes of growth hormone all throughout the day, so you're body's actually trying to build a pair assuming that you eventually eat again and provide the nutrients that are needed.  You're body actually goes into that anabolic home.”

Ben:  Hey folks, it's Ben Greenfield, and I have to admit that probably thousands of books have been written about diets that help people lose weight or get better health or whatever, get into ketosis or become a vegan or learn how to barbecue, whatever.  But one of the things that tends to be a prevailing theme from diet to diet in terms of actually moving the dial when it comes to health is periods of time where you simply stop stuffing calories into your gaping maw, and that's what today's podcast is about.  It's about something that you find spread across religions, something you find spread across diets, something you find spread across cultures where there's a lot of longevity, and that's this concept of fasting, and when fasting is done right, it's got an incredibly effective therapeutic effect on a lot of different diseases.  It also, of course, has a fantastic effect on things like weight loss and Type-2 Diabetes and obesity, and my guest today, in addition to recently writing what I would consider to be the ultimate guide to fasting.  It's actually called “The Complete Guide to Fasting”.  Even though it was me, I would have named it “The Ultimate Guide to Fasting”.  His name is Dr. Jason Fung.  He is Toronto-based.

Dr. Fung:  Hey, how are you?

Ben:  Hey, I'm good, man.  I'm good.  You're a nephrologist which means you're a kidney expert in Toronto, and you're still practicing as a nephrologist, right?

Dr. Fung:  Oh, absolutely.  Yes.

Ben:  Okay, cool.  And then for those of you curious about Jason, he also the chief of the department of medicine at Scarborough General Hospital.  He on the board of directors of Low Carb Diabetes Association.  He's also the scientific editor of the Journal of Insulin Resistance, and he knows what he's talking about.  He's a smart cookie, and we're going to be able to dive into his brain, and find out everything he knows about not eating.  So, Jason, welcome to the show, man.

Dr. Fung:  Thanks very much, great to be here.

Ben:  I guess the million dollar question is are you fasted right now?

Dr. Fung:  Yes, I am.  I don't eat breakfast a lot of the days of the week, so when I have something at lunchtime, then I'll often just keep working, and once you get used to it, it's really not very difficult because the body will simply take the calories it needs from your stores of energy which is your body fat and the glycogen which is stored away.  So it's a completely natural process, and when there's time then I go and eat.  It makes it so much easier.  You don't have to obsess all the time about I don't have time, why can't I eat?  Then you wind up going to the local doughnut store, and then oh there's just muffins.  And then you know that that's not good for you, but then you feel this pressure to eat.  There's some of this pressure on people oh, you're not hungry, but you must eat.  Eating when you're not hungry is not a great weight loss strategy.

Ben:  Yeah.  Now what about, not to play devil's advocate right of the bat, man, but what about this concept of circadian rhythmicity and the fact that you'll see a lot of recommendations that to optimize circadian rhythms or to have a good body clock that it helps upon waking within a few hours after waking to actually consume a meal.  Are you concerned at all about circadian rhythm?

Dr. Fung:  No, in fact if you look at what happens when you wake up, it's very interesting because there's a counter regulatory surge which happens just before you wake up.  So somewhere around 4, 4:30 AM, your body releases certain hormones which are counter regulatory hormones.  That is they run counter to insulin.  So these are the sympathetic nervous system gets activated, growth hormone nor adrenaline for example.  So these all spike just before you wake up, and the whole point of it is that they are actually activating your body for the day ahead, and one of the things that these counter regulatory hormones do is they stimulate your liver to pump out some glucose.  In fact, you don't have to eat to get ready for the day.  Your body's already done that for you.  If you start to eat, well that's fine.  If you like to eat breakfast, it's fine, but you don’t have to.  There's no magic about it.

Ben:  Oh yeah, I wasn't saying you have to, that you're going to run on energy 'cause what you're saying makes sense in terms of glycogenolysis by the liver and production of glucose.  What I was just curious about was some of these studies I've seen about habitual meal frequency and its effects on a normalize circadian rhythm or better sleep later on in the day.  Basically the relation between nutrition and circadian rhythm in mammals I know has been pretty well studied, but I was just curious if you'd thought about that much at all.  I don't remember seeing that part in the book, things about how regular eating might affect the circadian rhythm.

Dr. Fung:  I don't think that it makes a big difference because lots of different cultures have done all kinds of different eating regiments throughout history, and people have done well on all different ones.  If you look at for example circadian rhythm of hunger, I actually think that's very interesting because if you take people and simply measure their hunger, over 24 hours there is a tendency to go in certain patterns, and the rhythm is that your hunger's actually lowest at somewhere around 7:30, or at 8 o' clock in the morning.

So again, and that's because of the counter regulatory surge, and the fact is that the hormones is what determines your hunger 'cause 8 AM is usually the longest period before you've eaten 'cause you've often not eaten all night, so it's maybe 12, 14 hours since you've eaten, yet your hunger is actually the lowest that it is through the day.  So again, that's why a lot of children don't feel like eating breakfast and so on, and the only reason they start eating breakfast is that we force them and we tell them that you got to eat breakfast, you got to eat breakfast, you got to eat breakfast.

And it's okay if you don't want to eat breakfast, but what you want to avoid is eating all this processed, sort of highly refined foods that are so convenient and have taken over the breakfast aisle so to speak because they're so easy we can grab them and go.  Muffins and doughnuts and all these pop tarts, all these sort of things that are super unhealthy for us because we don't want to cook bacon and eggs in the morning, it's like who's got time for that?  You got to cook, clean, eat, all this sort of stuff.  So even if you look at the circadian rhythm, again if you're the least hungry at 8 AM, why would you force yourself to eat?  It doesn't make any sense.  It's based on people who have said that oh, it's going to keep you full throughout the day, it's going to boost your metabolism.  The data behind those claims is very, very sketchy.

Ben:  Yeah, it makes sense, and where I'm at is typically wait for about three hours or so after I get up to eat, and if I finish dinner at around 8 PM, usually I'm eating breakfast around 9:30 AM, 10 AM, and so I'm halfway between.  I eat, but I eat late when I get up.  Now my kids, they are not cornflakes kids, they are not pop tart kids, but they get up and make elaborate breakfast.  My twin nine year old boys will get up, and they'll do the full-on.  They got to be on the bus by 7:30, and they're up at 6:30 like scrambling eggs, making waffles, getting mom's nut butters and jams out of the pantry, and they do a full-on spread for breakfast, plus their little hearts.

I know that's probably 'cause they're running around all day at school, but then the interesting things is they will come home having barely eaten any of the lunches that we packed for them like carrots, and olives, and avocado, and pemmican, and all these things we send them to school with, and then they'll play and play and play and play and typically eat dinner at about 7:30, 8 PM, or so.  So they kind of do a two-a-day meal type of thing, but it's interesting to watch children and see what they might naturally progress towards, although I think their affinity for breakfast also comes on the fact that mom's a big breakfast person too.  She's making the homemade cinnamon rolls, and ferment the waffles overnight.  She's very much into that.

Dr. Fung:  Yeah, and as I said, there's nothing intrinsically wrong with it, but people get brow-beaten into oh you must eat, you must eat.  There's lots of different options.  You can eat if you want, and you can make it work for you.  If you're really not hungry at breakfast and you don't want to eat and you want to rush out the door to get to work and get to school, yes, you can just skip it and go to lunchtime.  It's okay.  What's interesting is the very word itself, breakfast, it's the meal that breaks your fast.  It's not the, oh you must eat as soon as you wake up before your feet hit the ground, sort of thing.

You can break your fast at any point, you can break it at 8 AM, and you can break it at 11 AM.  It makes no difference, and the other thing that's very interesting word is that what it implies is that you actually have to fast in order to be able to break your fast.  So what this tells us is that it's part of the natural cycle of life.  You have to eat, but you have to fast.  Fasting is merely the absence of eating, so if you have a period of time that's when you eat, then you have a period of time where you should fast.  You don't eat all the time.  That's not a good weight loss strategy either.  We get told again and again, oh before your feet hit the ground, you got to start shoving food into your mouth.  And then, oh you can't, you have to eat all the way up until you go to bed.  Six or seven, eight, nine, ten meals in the day, oh that's going to make you healthy.  Where is your period of fasting?

Ben:  It'll make you swell though.  I used to bodybuild, and that's what I did, and I was actually fooled into thinking that it would also increase the metabolic rate which is you've just eluded to.  It doesn't.  You don't need anything more, I believe, at this point more than two meals a day.  And I actually want to talk to you about this whole concept behind starvation mode and metabolic rate and how long you can go between meals, but I used to eat a ton of meals.  I'd show up at work with my yogurt and my carrot sticks and my apple and my chicken and my broccoli and my rice and my three different protein shakes and just graze all day long, and it actually worked pretty well for putting on a ton of muscle and weight on my body which is what I was trying to do at that point, but there's definitely some health implications too which I think this would be a perfect place for us to delve into some of the health implications or at least what happens from a physiological standpoint.

You have in the book, I guess you describe it in five different phases if I'm correct or five different stages in the book.  What happens when we stop eating?  Can you go into exactly what's going on when we stop eating from a phase one to phase five type of standpoint?

Dr. Fung:  Yeah, so this was described by a lot of the physiologists.  Many of these studies are very old, and it basically is a process of moving from storage of food energy to burning food energy.  So what happens is that when you eat, insulin goes up, and insulin is a hormone which essentially a nutrient sensors.  So a lot of things, other than just carbohydrates, a lot of proteins for example will also stimulate insulin.  When you eat, the insulin goes up, and it tells your body that you need to store food energy because you're eating and you've brought more food energy than you actually need.  So some of it goes to open up the cells to glucose for example, and that's what we tend to think about for insulin is that it lets the cells use the glucose.  But the other think it does is it stops lipolysis which is the burning of fat and glycogenolysis which is the storage.  So you store sugar in the form of glycogen in the liver.  So glycogen is long chains of glucose.  The liver packages them all together and stores it in liver, and this is why you don't die when you go to sleep every single night is because your body can store some of this food energy.  So when you're not eating, it will bring it back out.

Plants for example will link all these chains of glucose together, and starches.  So amylopectin, for example, there's amylopectin A, B and C, so there's different forms of starches.  So for example white bread, white flour uses amylopectin A, and this is the wheat that puts all this glucose together.  So that's what plants do, they use starch and humans use glycogen and lots of mammals use glycogen as well.  But essentially, you can think of it as stored sugar because that's what it is, and the body has two storage forms of energy.  It can store glycogen, and when that's full, you can't store anymore because the liver simply can't hold it.  So your body then turns to storing fat, and this is the process of De Novo Lipogenesis.  So “de novo” is a word from Latin.  It means from new.  Lipogenesis, lipo means fat, genesis means the creation of, so it's the creation of new fat, but it's the creation of new fat from carbohydrates.  Dietary fat doesn't actually do this, it actually just gets absorbed directly and goes into your fat cells.

The excess carbohydrates, if you take a lot of carbohydrates, it gets turned into glycogen, it gets stored and then body fat.  So there are two complementary storage systems because they fulfilled different roles in the body.  The glycogen is easily accessible.  That is the body can move in and out of glycogen very easily, but there' a limited amount.  Body fat is much harder to get at, but it has unlimited storage.  So the analogy I sometimes use is it's kind of like a refrigerator and a basement freezer, like a chest freezer.  The refrigerator, it's right there.  It's easy to put food in, it's easy to take food out, but once you're full, you're full.  The freezer in the basement has unlimited capacity, that is you can put several freezers downstairs, but it's harder to get to, and that's how the body stores energy.

As you stop to eat, so the process of fasting goes through several phases.  When you eat, insulin goes up, you store food energy in those various forms.  You'll notice of course that protein is not stored as energy.  If you eat a lot of protein, then your body uses some of that protein for building protein, but the excess actually just gets turned into glucose 'cause it can't store that excess protein.  It's very hard from a dietary standpoint to eat a high-protein diet.  It tends to be very unpalatable, but if you're pounding back whey shakes and protein bar, a lot of that excess protein is syncing.

Ben:  It depends man.  I don't know, rib-eye steaks are pretty tasty.

Dr. Fung:  Yeah, natural foods of course are good, but it tends to, when you're just eating, there' a lot of fat in there as well.  But just to have those shakes and stuff, which is kind of pure protein, it's not that effective.  It's not as effective as you'd think it would be.

Ben:  Good for the biceps though.

Dr. Fung:  Yeah.  (laughs)  A lot of bodybuilders use that sort of protein supplements, but you got to realize that the bodybuilders are actually breaking down a lot of muscle all the time because they're working out.  They're breaking down the protein, so they may require more protein.  So the first phase is the eating phase, then you start to go into the fasting phase.  So from about 0 to sort of 24 hours, what happens is that your insulin starts to fall.  So the food that you eat is gone, and now you need to start pulling out energy.  So you need to start pulling energy back out from the body in order to keep it working.  So the first place it goes is the glycogen.  So what you see is that your body continues to burn glucose up to about 24 hours.

At about 24 hours, the glycogen stores run out, and there's a period of gluconeogenesis.  So gluconeogenesis is again, from the word gluco meaning glucose, neo which is neogenesis creation of, so it's the creation of new glucose.  It gets created from proteins, so you will break down some protein and create glucose in order to feed the cells.  You're ramping up fat oxidation at the same time, but that takes a little bit of time because as I said, the fat stores are very large or can be very large, but they're difficult to get at.  So it takes a little bit of time, so in that 24 to 36 hours, you get this period where you're actually breaking down some protein, you're still living off the rest of your glycogen, and then that's it.  After 36 hours, then you get the kind of fat oxidation starts to take over.  So protein burning really drops to a minimal turnover and then the breakdown, and then you start to see the fat oxidation, so fatty acid levels go up in the blood, and you see fat in the blood.  Basically the body lives off of stored fat from then on.

Ben:  And that's basically ketosis right, when you get to that point of 36 hours in?  Although you're not saying to get these effects, you would have to say go 36 hours with zero calories at all, but what you're saying is if you were to, this is what would happen.  So whereas some people would take a couple weeks of low calorie intake, high fat intake, restriction of carbohydrates to really begin to efficiently enter ketosis if you just go three days without eating period, you get there a lot faster?

Dr. Fung:  Exactly, so this is just physiologically what happens when you stop eating.  There are ways to hack the system, so to speak, so ketogenic diets for example will use very, very high fat diets in order to reduce serum insulin because insulin's one of the master hormones that controls where your energy is coming or going.  You have to understand that insulin is essentially a hormone that tells our body to store energy.  When insulin is low, your body wants to burn energy, but you can't do both, and this is something that's very interesting.  And it makes sense because if you're burning energy, you don't want to store it and vice versa.  So if insulin's high or it's low, the effects are completely opposite.  And there's something called the Randall Cycle in physiology as well is that when your body is burning glucose, it's not burning fat.  And when it's burning fat, it doesn't burn glucose.  And this is a system that's designed because you want to kind of use one fuel or the other, and not both at the same time.  It's not very efficient, so that's why there's this sequential move from burning glucose at first and then fat, and that's how you hack the system because if you have super, super, super low carbohydrate intake, you essentially are just providing fat to the body.  Obviously there's some protein there, but mostly fats.

Ketogenic diets, for example, are very high fat diets, and because it's mostly fat, you're body turns to burning fat which is why you get ketone production.  Actually most of the body doesn't use ketones.  Most of the body directly uses fatty acids.  So the triglycerides, so body fat is triglycerides, it's a glycerol backbone with three fatty acid chains.  As you break those fatty acid chains off, muscles will use fat directly.  The glycerol gets turned into glucose because certain tissues need glucose.  The brain is one, but the brain uses way too much glucose.  So in order to get the fuel into the brain, your body produces ketones which will cross the blood-brain barrier and feed the brain, and that reduces the reliance on glucose.  So that's where ketosis is, that's where ketogenic diets are, and that's how people gain the system to get where they want to go.

Ben:  But no matter what kind of diet you're eating, whether it's a centered American diet, or whether it's the McDonald's diet or whatever it is, if you stop eating for three days, you'll be in ketosis basically.

Dr. Fung:  There is a good chance.  Now there is something called the glucose-ketone ratio.  Different people are actually quite different.  It's interesting that as your glucose falls, you expect your ketones to go up, but that's not what happens in everybody.  So some people actually don't bring up their ketones, and that's why people get this keto flu or they don't feel so good when they're not adapted to that because ketones don't respond normally.  Most people will go back to it very quickly, but yeah, if you don't eat, that's a very fast way to get into ketosis for the large majority of people.

Ben:  Got it, okay cool.  And then finally, so that would be the fourth stage.  You've got your feeding stage where you actually have glucose that you talked about, getting stored as glycogen in the liver or getting converted to fat, and then what you call the post-absorptive phase which is 6 to 24 hours after you start fasting where your liver starts to break down its own glycogen, and the glycogen stores last until that 24, 36 hour mark.  Once glycogen runs out, then you begin to manufacture the glucose from amino acids and proteins, then you go into ketosis, and then you have this final stage called the protein conservation stage.

Dr. Fung:  Yeah, and that's where you're essentially just burning fat.  So fat oxidation goes up when you measure.  Where are people getting their energy from?  It's from the fat, and that's great because that's really what we want to do.  We want to burn the fat, and this is very important because the period from 24 to 36 hours roughly, where people are burning protein, that's where people get the misconception that you're going to lose muscle, you're going to burn muscle, you're going to burn muscle.  If you're just to look at that, you might think that makes sense.  But what they miss is that when you start re-feeding, when you start eating again, growth hormone levels have gone way up.  So again, remember that growth hormone is one of the counter-regulatory hormones.  So norepinephrine, growth hormone, the sympathetic nervous system all go up as your insulin goes down.  So growth hormone is going up, so when you actually start to eat again, you are starting to rebuild all that lost protein, but it's actually better because what you've done is when you break down those protein, your body actually identifies the kind of old, junkie proteins that it doesn't need, the cell that it doesn't need and gets rid of them and then rebuilds new ones.

So it's actually a complete renovation cycle as opposed to leaving that old protein where it is because if you continually eat all the time, you don't have that breakdown.  That breakdown is very important in medicine for example, for new bone.  You don't simply have the bone just sticking around.  There's actually a continuous cycle of renewal, of breakdown and regeneration, breakdown and regeneration, and this is what the fasting does.  It gives you that period of breakdown and regeneration.  So if you look at studies of alternate daily fasting for example, they've done studies where they've compared calorie restriction with alternate daily fasting over a period of 32 weeks of measured lean mass at the end of it.  In fact, the calorie restriction people, their lean mass percentage went up by 0.5% because they had lost some weight, but the alternate daily fasting went up by 2.2%.  So in other words, the fasting group was four times better at preserving lean mass.  Absolutely, and it's directly contrary.

Ben:  And that's because you get high levels of growth hormone that maintain muscle mass and lean tissue when you're at that fasted state, and that's related to this protein conservation phase you talk about?

Dr. Fung:  Absolutely, and this is what's very interesting because you have studies of people who are growth hormone deficient.  For example, older men.  Some people when they measured growth hormone and they're deficient and then replace them, they see this increase in lean mass, increase in bone mass and all these really beneficial things.  So I think that that's what people miss when they just look at that period of gluconeogenesis when it's breaking down.  They miss that period when you're rebuilding.  Just like if you were to do a renovation, you have to tear stuff down first.  You have to take down all the old cabinets before you put up new cabinets.  So if you're just looking at the tear down, you say oh, that's terrible, but you haven't looked at the full cycle of feast and fast which is much more powerful.

Ben:  It's kind of interesting because usually you would think that not eating would actually fly in the face of anabolism, that not eating would potentially suppress something like growth hormone.  But what you're saying is over a fasting period, and I think you even have some research that you go over in the book.  You actually see a significant growth hormone increase, like you talk about the religious 40-day fast where baseline growth hormone levels went from 0.73, it's like nanograms per milliliter, up to almost 10, 12,050% increase in growth hormone without any drugs or injections just from not eating.

Dr. Fung:  Yeah, it's fascinating because you would think that it's the opposite.  Hey, if you're eating a lot, your body's going to produce growth hormone, but it’s actually opposite very interestingly enough because growth hormone is a counter-regulatory hormone, so as you eat, insulin goes up, so growth hormone goes down.  Nothing shuts down growth hormone secretion like eating.  It's fascinating, when they do these long fasts, five days and so on, the growth hormone levels just go way, way up.  When you see the pattern of growth hormone secretion, you get this big spike in the beginning of the day.  During that period of longer fasting that most people have, that 12 to 14 hours where you don't eat, once you start to fast where you just don't eat anything at all, you start to see little spikes of growth hormone all throughout the day, so your body's actually trying to build and repair and so on.

Obviously if you fast forever, you'll die, but assuming that you eventually eat again and provide the nutrients that are needed, your body actually goes into that anabolic mode.  So it is fascinating, and I wouldn't have thought of it logically either, but this is physiology.  This is what happens when you know that nothing turns off growth hormone like eating.

Ben:  Yeah, and basically in terms of conservation of lean muscle mass, if you're fasting, what you were saying is based on what you were talking about with this Randall Cycle, carbohydrate oxidation is going to go down towards zero.  Fat oxidation is going to increase, and when fat oxidation increases, the normal rate at which you'd break down protein, even if you were eating normal meals, goes way down.  Your body actually, naturally kicks in to protein conservation and growth hormone increase in the absence of food.

Dr. Fung:  Yeah, that's just the normal way of things.  So fasting provides a lot of different hormonal changes.  There's changes in obviously insulin and norepinephrine and growth hormone, sympathetic nervous activation.  This is one of the other things that people don't necessarily understand is that if you think about what these hormones do, they actually activate the body.  So sympathetic nervous system is the so called fight or flight response, so the body's actually getting activated during this period of not eating norepinephrine or adrenaline, which is noradrenaline, is pumping up your body.  It's not shutting it down, and this is what they say.  Oh you don't eat, you're going to go to starvation mode.  You're basal metabolic rate will go down.  It's the complete opposite.

When they say you'll go into starvation mode, they're actually not just wrong.  They're like hundred percent wrong because it actually activates.  So people come back from fasts and they go “Woah, I cannot believe how much energy I had.” Yeah, because your body is pumping you full of energy.  And if you think about it from an evolutionary standpoint, for example, it makes total sense.  If you are a hunter and a caveman and you don't eat for a couple of days, your body starts to shut down.  You will never eat again.  You have no energy to go out and hunt.  You have no energy to catch those rabbits, whatever.  So your body simply not that stupid.  What it does is it switches energy sources.  So it says, “Okay, there's no more sugar.  I can't burn any sugar.  I've run through my glycogen.  I need to switch to body fat.  Not only am I going to switch to body fat, but I need to pump you up, so that you can go out and hunt some woolly mammoth.  Otherwise, I'm going to die.”  So that's what it does.  So it actually burns fat, pumps you up, gives you more energy, and it's exactly what you want to do because the alternative is not viable, but these are physiological responses.  It's not just hocus pocus.  You can measure these hormones, and you know what noradrenaline does.  It pumps you up.

Ben:  So you're saying your basal metabolic rate is not going to decrease at all from fasting?

Dr. Fung:  In fact, it's the exact opposite.  When you measure people after prolonged fast, their basal metabolic rate goes up.  So for example, a study I sited which measured metabolic rate after four days of fasting shows that when you measure the resting energy expenditure at the beginning and the end of the fast, it's about 10% higher at the end of those four days.  So your body's not shutting down.  It's actually being pumped up.  So all this stuff about, “oh, you should never skip this meal because you're going to go to starvation mode”.  They're completely wrong because your body is pumping up, not shutting down.  In fact when you do calorie restriction, we know from study after study, all those studies on the Biggest Loser for example, that if you simply try to reduce a few calories per day, so if you say, oh I'm going to go from 2,000 calories to 1,600 calories per day.  We know that your energy expenditure is going to go from 2,000 down to 1,600.

You will for sure go into so called starvation mode, but it's the calorie restriction that does that.  Why?  Because your body remember has two sources of energy.  It has food, and it has stored food, or body fat.  So if you keep eating, insulin is high, your body says I need to store energy, but you only have 1,600 calories.  You're body wants to burn 2,000, but it's only getting 1,600.  Your insulin is high, so you can't store energy and burn energy.  Insulin is high, so your fat stores are locked away.  You can't access them 'cause you're still eating all the time, and what it does is simply I'm getting 1,600 calories in.  I'm going to reduce my expenditure to 1,600, so you've gone down.  The difference when you go down to zero when it's about moving that insulin way down is that all of a sudden, you've unlocked all those stores of fat.

Ben:  Okay, so basically it sounds to me what you were saying is if you go in a restricted calorie diet, if you drop from 3,000 calories and you down to 1,500 calories a day for let's say four weeks for losing weight, your insulin levels are still going to be elevated from the eating that you are doing and the combination of high insulin and reduced calories would actually slow, not speed up your metabolism.  That would be a case where calorie restriction would actually slow the metabolism.

Dr. Fung:  Yeah, that's what the study shows is that almost all these attempts to simply restrict your calories.  Now insulin won't go down because insulin goes down whenever you eat anything.  Assuming your diet doesn't change much, but you eat a little less.  Your insulin will go down slightly, but it's not going down to zero.

Ben:  It's not going down as low as it'd go if you were fasting?

Dr. Fung:  Exactly, and low-carbohydrate ketogenic diets do a pretty good job also if bringing that insulin level down with it.

Ben:  Okay, so basically if you were going to restrict calories and you didn't want to get the drop in metabolic rate associated with calorie restriction, you would need to make sure that you were either measuring insulin or else eating foods like whatever, coconut oil, avocados and olive oil that weren't actually going to spike the insulin levels but still allowed you to consume a lower number of calories?

Dr. Fung:  Yeah, it's really about the insulin, and then actually you can lower the insulin levels even with a high carbohydrate diet.  It's just that it's not sugar and refined grains.  So there's lots of ways, beans for example.

Ben:  Yeah, like lower glycemic index foods.

Dr. Fung:  Exactly, because the glycemic index is good for carbohydrates, not for the other foods, but it's a good reflection of what the insulin response is.  There's a huge difference, for example, between beans and white bread.  So they may be the same number of grams of carbohydrate, but the insulin effect, the glucose effect is hugely different, and you see it on the glycemic index, so therefore, if you look at some traditional societies, for example, they ate a very high carbohydrate diet, but their insulin levels were not that bad.  The key of course is that they're not eating sugar, they're not eating refined grains, and they're not eating all the time.

So when you do that, you can tolerate these carbohydrate foods.  So natural carbohydrate containing foods, unprocessed sort of things, don't have nearly the insulin effect as our refined, highly processed foods that we kind of eat in modern day North America.

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Ben:  Hey, I want to interrupt today's show to tell you about something very, very cool that you can do.  So if you're injured, or you're sore, if you've got some nagging aching pain, there's this three-step method that I use.  Step one, I put a little bit of magnesium oil or some other topical anti-inflammatory, could be arnica, magnesium, icy-hot, whatever.  Next, I slap some electrodes on, and I cover up the electrons with kinesio tape or some kind of tape, you can even use duct tape in a pinch if you're a true redneck, and that holds the electrodes on.  Then you cover that with ice, so you can jack up the electricity that you deliver to said area to increase blood flow, to decrease inflammation and to enhance recovery.

Now, the electrical muscle stimulation that I use for this that you actually don't have to combine with a topical and with the ice, that's just my little biohack.  It is called a MarcPro.  This thing is freaking amazing because unlike the other electrical muscle stimulation units that are out there that use what's called a square waveform, this uses something called a, propeller hats please, dynamic decaying waveform which makes it not only one of the only major recovery products that is FDA-cleared for pain relief, but it means that it grabs your muscles in a very therapeutical way that causes no damage and that enhances recovery.  It can be used for conditioning, it can be used for performance, it can be used for massage, and it can be used for warm-up.  You name it, it's an amazing unit.  I actually have it right now in my car because I've been using it while I'm driving on my back.

So it's called a MarcPro, MARCPro, and you go to marcpro.com, and you get your discount, 5% discount which winds up saving you a lot of cash with promo code “Ben”.  So use promo code “Ben” to get a 5% discount on the MarcPro Electrical Muscle Stimulation.

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Ben:  Now what about though, to play devil's advocate again here, there's this story of the Biggest Loser contestants and how a whole bunch of them, they weren't eating that much food, they were exercising a ton, but I believe in the study that showed how they all or many of them have this shocking increase in weight, this yoyo weight gain effect after the show.  Didn't they show that they actually had a drop in their metabolic rate during the show or after the show, or something like that?

Dr. Fung:  Absolutely, so their metabolic rate was started dropping immediately.  So the Biggest Loser diet is really the same standard sort of eat-less, move-more advice that physicians and dietitians have given, but it's sort of that eat-less, move-more on steroids.  It's eat a lot less and move a lot more.  So their calorie restriction goes down to about say 1,200 calories, something like that.  They don't want to be accused of starving their patients, which I think is ironic because I think if they went to zero, they'd have done a lot better.  And their exercise goes way up because on the show, you see them exercising and throwing up and all this kind of stuff.  So it's essentially the same advice that people give, eat-less, move-more, but kind of jumbo-sized.  And what they show is that their metabolic rate just plummets.

So as they lose weight which they do in the short term, they're metabolic rate also drops, and because their metabolic rate drops, they're feeling more tired and more cold, more hungry, and the worst part is that because they're burning less calories even as they're eating less calories, their weight loss slows, eventually plateaus.  So now, your weight is not dropping, but you're burning 1,200 calories instead of 2,000.  So your liver doesn't get enough energy, your heart gets less energy, you're not generating body heat, you feel really crappy, and your weight is still down.  So as you relax that, you start eating say 1,400 calories, but you're only burning 1,200, so that weight comes right back.  So you see on that six-year study that some people wound up fifty pounds heavier than when they started the whole thing.

Ben:  It's crazy, but what you're saying is that might have not even happened if they would've just for example either a), fasted and done some low intensity exercise that wasn't incredibly catabolic in that fasted state, or b), if they, for their caloric restriction, would have chosen a form of caloric restriction that doesn't increase insulin levels, like a ketogenic diet, or a slow carb diet or something that allowed them to not get the metabolic decrease accompanied with what they were doing which was a standard low-calorie diet that didn't control insulin levels combined with massive amounts of exercise and puke fests.

Dr. Fung:  (laughs) Absolutely, I think it's about controlling insulin, not about controlling calories.  So you can do it many different ways.  There's paleo diets, and so on.  Intermittent fasting just happens to be one of the better studied ways to maintain your basal metabolic rate.  So we know from our studies, from physiology studies that this is what happens, so why don't we use our knowledge to tweak it.  I mean, I don't say that everybody needs to fast or should fast.  It's not easy, it's not fun, but why don't we let people use it as an option?  If you don't eat, you're going to lose weight.  That's not that hard to understand.

What you have to understand too is that this is completely natural, and when I talk to physicians, physicians always understand this point because I say to them well, we tell people that they should never ever miss a meal.  If you miss a meal you're going to die, but we tell people to miss meals all the time.  When they have surgery, you have to fast.  When you do a colonoscopy, you have to fast.  When you do fasting blood work, you have to fast.  When you do an ultrasound, you have to fast.  So there's all these situations where we actually tell people to fast.

And guess what?  Nothing bad happens, everybody's normal.  They might be hungry, they might be a little cranky, but that's about it.  Nothing bad happens, so why can't we simply use that as a therapeutic tool to make people lose weight because these people have Type-2 Diabetes, they're obese, they're having heart attacks, and they’re having strokes.  This is a serious problem to leave them at that level.  The standard advice to eat less and move more doesn't work.  We all know it, and the studies all show that it doesn't work, so why shouldn't we use this tool that we have which is honestly the most powerful weight loss tool because you cannot go lower than zero calories.  You can't go negative calories.  So therefore, this is the most powerful tool, and we've decided to not use it?  Are you kidding me?  That's got to be the craziest thing I've ever heard.

Ben:  It's not fun, you get hungry, man.  Actually I wanted to ask you about that 'cause you get hungry, but what I've noticed 'cause I do throw in a 24-hour fast.  I've been doing it about two to four times a month.  I'll go from Saturday night until Sunday night, and then I usually have my big rib-eye steak and sweet potato fry chow down on Sunday night.  Anyways though for the first few hours of the morning when I wake up on Sunday, I'm kind of hungry once I get to the point where I'd normally eat breakfast.  Around 10 AM, I start to get hungry, and from 10 until 1 on a Sunday if I haven't eaten on a Saturday, like if I stop eating Saturday dinner around 8 PM, I get up Sunday, I go about my normal routine, I get to the point where I'd normally eat breakfast, and then I start to get hungry, and then around noon, 1, I get super hungry, and then an hour later, it goes away.  What's going on though?  Why do you get hungry and then it gradually goes away once you get to a certain point in the fast?

Dr. Fung:  Yeah, this is the very interesting thing because everybody assumes that you can't do it because hunger will just build and build and build, and then it'll be intolerable, but that's not actually what happens.  You can look at the so-called hunger hormone ghrelin, and if you take somebody and you fast them, you can measure their ghrelin levels and see what happens.  So in normal people, you get this three sort of spikes at breakfast lunch and dinner, so clearly there's some element of learning involved because we expect to eat at 12 o’clock, we expect to eat.  Our body preempts us and expects it and puts out ghrelin.  But what happens when you don't eat, when you skip that meal is that the ghrelin does not continue to go on.  It just falls back towards baseline.

So that's really interesting because again, when I speak to physicians, they all know this because we, all during our residency medical student days, we missed meals all the time.  We're just way too busy, and you don't have 45 minutes to sit down at the cafeteria, so you skip lunch and that's it.  So you're a bit hungry during that hour, and then once it's faded, so at twelve o' clock to one o' clock, you're a little bit hungry, but you're so busy, you just keep working.  By two or three o' clock, you've forgotten that you didn't eat.  And then sometimes you go high, I wonder if I ate today, and you didn't, because the ghrelin has gone completely back to baseline.

So over the day, this hunger actually comes in waves.  When people know that, they can plan for that, so I say, well you know it's going to come.  Prepare for it.  Keep yourself busy, have some tea, have some coffee, drink something, and let that wave just ride over you.  Let it pass, and then by two or three, it's done, and basically what you've done is you've let your body eat lunch or dinner whatever, of your own body fat, and that's perfect.  That's exactly what we wanted to do.  And when you look at multiple days of fasting, it's even more interesting because after about day one, day two, the ghrelin which is the hunger hormone peaks, and then starts to go down.  So this is exactly what we see in our clinics.  So when we have people doing longer fasts, five days, seven days, fourteen days, everybody says, “wow, how can you do that?”  And the secret is that after day two, the hunger slowly fades.  On day two, you are like, “wow, I will never get through this seven day fast”.  On day five, you're like, “wow, I could go on forever”.  The hunger has completely disappeared.

Ben:  And it's because the ghrelin hormone basically just gets depressed, goes away, and at that point, you don't want to eat anymore?

Dr. Fung:  Exactly, because now your body is just feeding you body fat constantly.  The levels of body fat, the fatty acid levels are high, so your body's like why do I need to eat?  I have tons of fuel here because you've shifted fuel sources.  So again, people always get the wrong idea.  They think it's a one compartment problem where all the calories goes in one box and all comes out of one box.  It's a two compartment problem.  There's the food and there's the stored food, and what you've done is you've shifted your fuel to come out of the body fat, and now there's just so much of it, and it's interesting because by day five, day six, and not everybody, but some people go, “wow, I cannot believe how good I feel.”  It's like their energy level is way up because the noradrenaline, the sympathetic nervous system.  I have no hunger at all, and a lot of people also note the sort of mental clarity which is been remarked over and over again, how they think that they're much sharper, more clear, and it's like, “wow, I feel amazing, and it's like wow.”  I mean, not everybody's going to be like that, but if people have this natural physiologic response and they do well, why don't we let them do it?  And then they'll lose weight because if you don't eat for seven days, you will lose weight.

One other thing that I would warn people about though about weight loss is that there's a lot of water loss.  This is what people will tell you.  The amount of weight loss, the amount of fat loss on a fasting I sonly averages half a pound of fat per day 'cause a pound of fat is roughly 3,500 calories, so if you're eating normally 1,800, 2,000 calories, it'll take two days to burn one pound of fat.  So on a seven day fast which sounds really extreme, you can expect to lose three and a half pounds of fat.  That's it.  So if you have a hundred pounds to lose, and you say, “wow, I'm expecting the seven day fast to do a lot.”  You have a hundred pounds to lose, and you lost three and a half, that's it.

You will lose more because the rest of that is water.  So you will probably lose seven pounds, ten pounds even, but if you lose ten pounds, six and a half of that will come back, so that you're only three and a half down at the end of the seven days, and that's where people say, “oh, you failed because look.  You lost all that weight, but seven pounds came back.”  Well you should have expected that that seven pounds was going to come back.  So you should have never expected that loss of water.  As it comes back, it's not a failure.  It's basically what you'd expect than having the experience when people understand this and expect it, then they don't feel so bad when this weight starts to go back up because you know that that's what is supposed to happen.  So it a very interesting thing.

Ben:  Yeah, it's like when I used to do bodybuilding, and you have to do everything from sauna to extreme carbohydrate restriction to salt restriction before you'd step on stage that you'd make weight.  As soon as you made weight, you'd step off and go do a pancake feed.  I could easily gain ten to twelve pounds within a few hours when I was doing that.  And it's kind of cool 'cause your muscles would be all swole, and you'd flex, and you'd feel like your biceps are going to pop through your shirt if you think that kind of stuff is cool.

Anyways though, I did want to ask you about these longer fasts 'cause you even get into extended fasting in the book.  Have you ever done one of these 'cause I've thought about it before just to push the reboot button on my body and get some cellular autophagy, and some of these other health effects that you talk about and that you also talk about in the book?  You know, not eating for two weeks, three weeks doing one of these water fasts?  Have you ever done one of those?

Dr. Fung:  I've never done a very extended fast because it simply doesn't fit into my schedule very easily.  I have to nerve with my family most of the time, so I do a lot of shorter fasts, the 24-hour fast.  I have done a few.  I'll tell you, the reason I did them was that I went on a cruise, I gained a lot of weight.  I wasn't watching what I was eating, and I made a decision that I wasn't going to watch what I ate, so I ate all kinds of crap like ice cream and desserts and all that, and everybody knows.  So I gained a ton of weight, and my rings weren't fitting, and I said okay, this is not good.  So then I went on a longer fast, though I think it was about three days, and I'll tell you.  At the end of the three days, then I went alternate daily fasting by the next week.  My weight was down to where it normally was, but I had a great time for that week.

I ate a lot of food that I don't normally eat, and I think that was probably the longest I did because I was starting to get a little worried when the rings weren't fitting and my pants weren't fitting properly and so on.  It was all the carbohydrates, right?  I'm not used to that high of carbohydrate intake, but again, that's as long as I've gone.  How long you have to go is unknown, so there isn't very much research into it.  If you'll talk to some of the people who have done these longer runs, they'll often say five days, seven days.  I'm not sure, I really don't know.  You can get a lot of the autophagy, cellular.  What you want to do is get into that 24, 36 hour where you're breaking down protein 'cause that's where you're getting that renewal cycle, the breakdown of the protein and then the regrowth.  And you can get a lot of those, Ben, if it's by 24, 36 hours, so I tend to do quite a few of those.

Ben:  The interesting thing though with the diabetics that you talked about in the study though is that they were completely, I think it was the two week mark with diabetes, you see people able to get completely off insulin just by obviously not eating for two weeks seems kinda sucky for some folks, but if you can reverse a freaking disease by just not eating for two weeks, to me that's pretty profound in terms of being able to completely off of insulin.

Dr. Fung:  Oh absolutely, but they won't maintain that.  You still have to maintain them, get them on the alternate day and monitor them.  So we do a lot of that for people.

Ben:  So you could fast for two weeks, and then after you've done that to maintain the health effects, you can do something like one of the other scenarios that you talk about in the book like 16-hour fasts each day or alternate day fasting or any of these other fasting scenarios.

Dr. Fung:  Oh yeah, absolutely.  We see this every day.  Almost every day I come in, and I see somebody who's completely off of their diabetic medications and so on.  One of the reasons we push some of the longer fasts is that these people are very sick.  That is we can do this in a controlled manner.  That is I can monitor them as a doctor.  We have bloodwork, we have somebody that they can call, if they have problems, we tell them to stop.  So it's a controlled situation, but the thing is that these are very, very high risk people.  If you don't do anything, they will develop a lot of different diseases, heart attacks, strokes, kidney disease, eye disease, amputations, and all kinds of things.  So the rewards are much higher.  So we will push the envelope a little bit more for these patients.  Now you can also do very well with shorter intermittent fasting, but it takes longer.  It's simply not as powerful as doing an extended fast, but again I would warn people that it is something that you have to adjust the medications 'cause you can't take the same dose of insulin for example and not eat, your blood sugar will plummet.

Ben:  Right, you get hypoglycemic, yeah.

Dr. Fung:  Exactly, so you have to do it in a safe manner which we try to do, but yes, you have to understand that Type-2 diabetes which is sort of very near and dear to my heart because that’s the majority of patients that I treat are Type-2 diabetes, and what we see is that when you put people on very low carbohydrate diets, when you use intermittent fasting, you can actually reverse the disease because their blood sugars will come down.  You'll take them off all their medications, and that's completely opposite to the message that comes out from the American Diabetes Association.  Most doctors which is that, “oh hey, Type-2 diabetes is chronic and progressive.  You've got it for life buddy.”  That's the message that comes out.  But it's not true because we all know that as you lose weight that diabetes goes away, so you have to be able to make them lose weight, but instead of that the doctor, such as what I used to do, instead of really working hard to make them lose weight so that their disease gets better, we would simply pump them full of medications, and I was guilty of that as much as anybody else, but I understood eventually that these people were not getting healthier.  They were getting heart attacks or getting strokes or getting kidney disease which is where I come in, and they weren't getting better.  Now I see their diabetes kind of melting away.

Again, it's not everybody.  Not everybody's going to do well with a fasting diet.  We're all individuals.  Some people do well with low-carb diets.  Some people sort of wild diets or paleo diets.  You got to find out what works for you, but what my main message is that these are options for people.  Don't take away those options of fasting, intermittent fasting, and extended fasting because some people will do extremely well on those.  Other peoples, they'll do terribly and they'll hate it, and they say well if it's not working and you hate it, don't do it.  Do something else.  But for those people who do very well, hey this is beautiful.

Ben:  Now what about when you stop this long fast though?  This is something you go into in the book.  I hadn't actually heard of it before.  I guess I have felt that effect of what my wife says is stomach shrinkage, after you've gone for a while fight eating and eat and your stomach feels weird or you get full really fast or you even get nauseous.  You call this Refeeding Syndrome in the book, and there's actually a reason for it.  You go into what refeeding syndrome actually is?

Dr. Fung:  Yeah, refeeding syndrome is actually something slightly different.  So during extended fasts, what you can sometimes happen, and this was described more in extreme [1:03:19] ______ prisoners of war in World War II for example.  When you start to eat, insulin goes up, but you're very malnourished at the beginning, phosphorous levels in the blood actually plummet.  So all the  phosphorous is going back into the cell due to the high insulin load of the food, and it gets so low that you can get heart arrhythmia, as in people have died for example.  So if you look at the risk factors for refeeding syndrome, it's more extended fasting, five days and beyond but also a baseline level of malnutrition.  That is people who were truly starving, holocaustic prisoners of war, that sort of thing.

Ben:  So it's like a mineral issue.  It's a phosphorous issue when your insulin levels go way up once you start eating again, and you get a bunch of synthesis of glycogen and fat and protein.  All that new synthesis exhausts your mineral stores with things like phosphorous and magnesium.

Dr. Fung:  Exactly.

Ben:  So if you're fasting, you should use electrolytes, but when you stop fasting you should definitely do something like you could use just trace minerals or sea salt and thing like that?

Dr. Fung:  Oh yeah, you could, but the key is that people who are not in that malnourished state are at fairly low risk of that.  So again, these are people who would be, for example, six-feet tall and ninety pounds.  They're so skinny, these prisoners of war.  When you apply it to people on what I apply to, they're 200, 300 pounds, the risk is very, very low, but you have to be aware that is a potential risk and it's out there.  The key is, and from when they've treated them in the past, as I've said I've treated over a thousand patients.  I've never seen it, but then I'm not treating ninety pound people.  I'm treating three hundred and ninety pound people.

So the risk is highly different, but you want to break the fast very slowly, so that insulin doesn't go up.  You want to try to avoid refined grains and sugar.  When you're refeeding, you want to go with more things such as proteins and so on, stuff with phosphorous, meat and so on.  You want to take it slowly so that it doesn't just shoot up, and in terms of the phenomenon where people say their stomach shrank, it's hard to know what that is.  Maybe it's the ghrelin which has gone down, but we've all done this where we've gone through extended fast and you go oh, I'm going to eat a lot, and then you eat a lot, and you got this big stomach ache, and everybody's gotten that.  Everybody who does fasting is like we've all gotten that, and it quickly teaches you not to do it because your body is actually saying no.  You don't need this, I've been feeding on my own fat, slow down, don't take so much because I don't want to switch back so quickly to all this stuff.  So it's very interesting because a lot of people will know this.  Yeah, I'm so hungry after my 36-hour fast, but then I eat a little bit, I'm completely full.

Ben:  Yeah.  It's because that drop in ghrelin that I think you're talking about, but I mentioned that I do that, the rib-eye steak feed on Sunday nights, but I got to do a little lemon juice and some bitters and sometimes I'll have a little vodka and kombucha or something like that.  By the way, you get just plowed off of one drink when you've fasted for any of you that wander about that, and then some of those digestifs get my appetite going.  I think I create some digestive juices, and then I'm actually hungry to eat, and food tastes really good, and in the absence of anything else, weed is great for breaking a fast because then you definitely get that spark in appetite then, and everything tastes great.  But yeah, you're right.  It's kind of weird you don't get that hungry.  You'd think that you'd get hungry, but for anybody listening in, just get Jason's book, and try a freaking 24-hour fast.  You'd be surprised at how easy it gets once you get past that craving you experience during the time that you'd normally have your first meal, and then you're just good to go.

Hey Jason, I wanted to mention something in your book I guess kinda in closing here if you don't mind.  I'm hoping you don't sue me if I read part of your book to folks.  But it says, “In the 1970s, a 27-year-old Scottish man started fasting at a weight of 456 pounds over the next 382 days.  He subsisted on only non-calorie fluids, a daily multivitamin and various supplements,” which I think were mostly minerals from what I understand.  “He set the world record for the longest fast.  His body weight decreased from 456 pound to 180 pounds, and then unlike these Biggest Loser guys even five years after his fast, he remained at 196 pounds.  His blood sugar levels went down, but remained within the normal range.  He had no episodes of hypoglycemia.” Boom.  So it can be done for a very long time.

Dr. Fung:  Absolutely, and this is the key when you look at these people who do hunger strikes and all this sort of stuff.  Everybody kind of says, “Wow, how can you do that?”  And again remember, once you get past day two, every day after that gets easier and easier 'cause you're actually feeding yourself body fat.  If you look at 382 days, half a pound of body fat per day is somewhere just less than 200 pounds, 190 pounds which is approximately what he lost.  So if you're looking to lose 180 pounds, and unfortunately there are people who need to lose that much.  That's the magnitude of the sort of caloric restriction that we're talking about.  You can go down to zero for that amount of time.

So it's funny because that's the world record that was monitored by physicians.  They wrote it up and so on, and it's like people can survive for 382 days, and we won't even let people go 24 hours without eating before somebody starts brow beating them into stuffing a muffin into their mouth.  It's hilarious, it's like, are you kidding me?  One other thing I would just say in terms of when you're getting into it, there is a period of adaptation where about two weeks, three weeks when you start fasting, there are lots of issues that come up.  It's kind of like exercise if you have never run in your life and then you ran and then your muscles are all sore.  You'd be like oh, running's the stupidest thing I ever did, but you have to give it time.  You have to get your body used to it, so your body's not used to the fasting, it's not used to shifting over to fat oxidation.

So it's kind of rusty, and it's not getting there.  So you may get this kind of keto flu where if you're not quite yourself.  You get a bit rain fog, you get a bit of this, get a bit of that, and what you have to understand is that happens to a lot of people, and the key is to just keep doing it, keep letting your body get used to it, and then after about two weeks, three weeks, four weeks, you'll find that it's like nothing at all.  So then now, for example, I can fast 24, 30 hours without noticing much at all.  Half the time when I'm really busy, writing a book for example, I'm like oh, I do tons and tons of fasting.  Not because I really want to lose weight, but because I just want that extra half an hour to do my work.  So then there's all these different benefits that come into play when you're fasting such as having extra time and so on.  That's terrific.  It's such a good option for people.  It's not a cure-all, it's not one of these miracle things, but at the same time you got to realize it's not like the latest and greatest fad, oldest dietary intervention in the book.  There's no intervention more ancient.  Don't eat for a while, that's what dogs do.  They get sick, they stop eating.  It's kind of this natural cleansing period that people talk about.

Ben:  It's funny.  That's what my wife does too.  She'll be like, I have a stomach ache, she's like I won't eat for three days.  My jaw drop 'cause I'm hungry watching her, but it works.  So it's interesting, and plus you've got a whole chapter in the book about these influential men in the history of the world like Jesus Christ, and Buddha, and the prophet Mohamed, Greek Orthodox, Christians, and monks, and Hindus, and all these people who have these pretty cool religious practices, they all have some element of caloric restriction or fasting.  And then of course, if Jesus Christ, Buddha, and Mohamed aren't enough for you, then you also get into some of these historical figures like Benjamin Franklin and of course, one of my favorites, Mark Twain who says, and this might be a good point to end on, “A little starvation can really do more for the average sick man than can the best medicines and the best doctors,” I love that.

Dr. Fung:  That's such a great quote.

Ben:  I'm going to link to the book for those of you who want to grab this book.  Just go to bengreenfieldfitness.com/fasting.  That's bengreenfieldfitness.com/fasting.  You can grab Jason's book.  The show notes for today's episode, you can leave your comments and your questions, all the goodness is over there.  Jason, thanks for coming on the show and sharing all this stuff with us man.  You make me really, really not to want eat which is weird but good.

Dr. Fung:  Yeah, absolutely, thanks for having me on your show.  It's terrific.

Ben:  Yeah, alright man.  Well folks, until next time, I'm Ben Greenfield along with Dr. Jason Fung, the author of “The Complete Guide to Fasting”, signing out from bengreenfieldfitness.com.  Have a healthy week.



Thousands of books have been written about the latest and greatest diets that will help people lose weight and improve health. But a key element in any successful nutritional health program is a tried-and-true method that most people haven’t thought about—yet it could be revolutionary for taking health to the next level. This ancient secret is fasting.

Fasting is not about starving oneself.

When done right, it’s an incredibly effective therapeutic approach that produces amazing results regardless of diet plan. In fact, Toronto-based nephrologist Dr. Jason Fung has used a variety of fasting protocols with more than 1,000 patients, with fantastic success.

Dr. Fung earned his medical degree at the University of Toronto, where he also completed his internal medicine residency before heading to the University of California, Los Angeles, for his fellowship in nephrology. He currently practices as a kidney specialist in Toronto. He is the chief of the department of medicine at Scarborough General Hospital. In addition to clinical medicine, he is also on the board of directors of Low Carb Diabetes Association and the scientific editor of the Journal of Insulin Resistance. During the course of treating thousands of patients, it became clear to Dr. Fung that the epidemic of type 2 diabetes and obesity was getting worse.

The prevailing dietary recommendations to reduce dietary fat and calories were clearly ineffective. He founded the Intensive Dietary Management Program to provide a unique treatment focus for type 2 diabetes and obesity: rather than focusing on medications, this clinic focuses on dietary changes that are simple yet effective.

In The Complete Guide to Fasting: Heal Your Body Through Intermittent, Alternate-Day, and Extended Fasting, he has teamed up with international bestselling author and veteran health podcaster Jimmy Moore to explain what fasting is really about, why it’s so important, and how to fast in a way that improves health. Together, they make fasting as a therapeutic approach both practical and easy to understand.

During our discussion, you'll discover:

-Why Jason and Ben have different takes on whether or not to eat breakfast…[8:25]

-The five different physiological stages of fasting…[16:45]

-Why growth hormone actually goes up, not down, when you fast, and how the body uses this mechanism to maintain muscle…[30:15] 

-Why fasting doesn't actually decrease your metabolic rate or cause you to go into to starvation mode…[33:20]

-What kind of scenario would actually cause your metabolic rate to decrease with calorie restriction…[37:10]

-Why most of the Biggest Loser contestants actually regained their weight after the show…[44:35]

-The reason hunger gradually disappears during a fast…[49:55]

-The shocking things that happen to your body when you do an extended fast…[56:35]

-What refeeding syndrome is…[63:00]

-And much more…

Resources from this episode:

The link between circadian rhythm and eating breakfast

The Complete Guide to Fasting: Heal Your Body Through Intermittent, Alternate-Day, and Extended Fasting

Show Sponsors:

Ample – Ample is a balanced healthy meal in a bottle with 20+ superfoods. Use code GREENFIELD for 15% off all first-time orders.

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Ask Ben a Podcast Question

5 thoughts on “[Transcript] – The Complete Guide to Fasting: How To Heal Your Body Through Intermittent, Alternate-Day, and Extended Fasting

  1. Denise Galiano says:

    Hey ,

    I know I am a year late watching this video but I was wondering if the book covers liquid fasting, how to do it and watch is acceptable to drink during it? Any suggestions on how to get that information.



    1. This is what the book covers: The Complete Guide to Fasting explains:

      • why fasting is actually good for health
      • who can benefit from fasting (and who won’t)
      • the history of fasting
      • the various ways to fast: intermittent, alternate-day, and extended fasting
      • what to expect when starting to fast
      • how to track progress while fasting
      • the weight loss effects of fasting
      • how to ward off potential negative effects from fasting

      Here is the link: https://goo.gl/h5Novu

      It does not go into depth on water fasting. Try listening to this episode to hear me in a recent discussion about this: https://bengreenfieldfitness.com/podcast/what-doe…
      This is a great place to ask this question: https://www.facebook.com/groups/getkion/

  2. Renu wasal says:


    Great pod cast, I had a question around adrenal fatigue especially in women. Why is it that there is a lot of literature warning about adrenal fatigue with intermittent fasting especially in women.

    I’m really quite confused about it.

    Would really appreciate your take on it.



    1. Renu, I'd really suggest reading the book!!

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