Fasting and Your Metabolism

Intermittent Fasting and Metabolism

Dr. Jason Fung Guide to Fasting

Jason Fung, nephrologist and best-selling author, shares his experiences utilising an individualised approach to fasting to successfully treat thousands of overweight, metabolically ill and diabetic patients and why being a doctor who specialises in kidney disease gives him a unique insight into early indications of metabolic disease. Let’s listen to Dr. Jason Fung. 

Dr. Fung’s focus on diabetes and obesity

Well, I’m a kidney specialist and the most important cause of kidney disease, by far really, is type 2 diabetes. So, when you look at treating type 2 diabetes, really, you have to take care of the obesity part of the equation because that’s really the most important part. So if you don’t treat it then everything else downstream doesn’t really get improved. So you can give medications but if you’re not taking care of the real problem, which is the weight problem, then the diabetes just continues to get worse. If the diabetes gets worse than the kidney disease gets worse. So you really have to trace it back from kidney disease all the way back to the type 2 diabetes back to the obesity and that’s really where you have to treat it. The thing about obesity is that we focus on, I think, the wrong issues, which is calories. We’ve been kind of brainwashed into believing that calories, too many calories, is what causes obesity and therefore you just need to cut some calories and you’ll lose weight. The trouble with that kind of thinking is that we’ve all done it and it doesn’t work. So if that doesn’t work and you don’t get the obesity problem solved then you can’t solve the problems down the line. 



The disease-pill problem

Medical training, that kind of conventional medical training through medical school and residency, really does not focus on it at all and I think that the standard teaching has us kind of in a sort of a 19th century medicine mode. What I mean is that if you look back at the diseases of the 19th and early 20th century what you’re dealing with there are a lot of diseases where there’s kind of infectious disease or there’s a problem and you take a medication and things get better. The problem, as we go into the 21st century, is that all our diseases are not that they’re not acute diseases or they’re not strep throat or some kind of bad flesh-eating bug or something like that, those still exist, but major problems are chronic diseases. We haven’t really been taught our mindset and medicine is really kind of “Here is the disease. Here is the pill to prescribe.” Yours kind of stuck in that mode. The problem is that a lot of the diseases that we deal with now obesity type 2 diabetes which leads to heart attacks and strokes and cancer and kidney disease and blindness and amputations. They’re all linked to type 2 diabetes and obesity, which are really dietary diseases. So what we’re doing is that we are using drugs to treat a dietary disease and then wondering why our treatments are so ineffective, which is stunning because you look at the rise and the epidemic of obesity and type 2 diabetes and you have to wonder, “Wow! You know we’re so smart, like humankind, we’re so smart.” We couldn’t put people on the moon, you know, we have these great computer technology and so on. If you look at computer technology, now compared to 1960, well it’s so much more advanced. We have much more genetic tools. 
But why is it that we simply have not been able to make a dent right? We have used all our human ingenuity, looked at this problem of obesity and declared that it’s all about calories. Nothing we do makes a difference because our paradigm, our whole premise of understanding the disease, is completely wrong. We assume it’s all about calories which is incorrect and we assume that the disease of type 2 diabetes falls into this kind of mode of “Here is the disease. Here is the pill that you need to give to treat it.” That’s not the case. The disease is a dietary one. So you need to go



back and you need to correct the diet in order for that disease to get better. So because we are stuck in this kind of old mode of thinking, we have let this huge epidemic run kind of underneath our feet. We have kind of let it go. 

“Calories isn’t the issue”

Well, here is the thing, right? So calorie is simply a measure of energy  and everybody thinks that “Oh, calories are calories.” Right? That is where it gets hot. Calories are calories but that’s not the question. Are all calories equally fattening? That’s the real question right because if you take a calorie, a hundred calories say of a food, your body can do different things with it. Your body can store it as fat or your body can burn it for energy and generate body heat. That is two very different things. The calorie is the same but as soon as you put those calories into your mouth depending on what it is, the instructions to your body as to what to do with them are completely different.

Cookies vs Salmon 

For example, if you have a thousand calories that you eat at dinner and you eat a plate of cookies every day for dinner versus you eat a thousand calories composed of kale salad with grilled salmon and olive oil, they are two different things but they’re the same number of calories. Common sense tells you that there’s nothing the same about those two. Okay? If you need to eat the plate of the every day for dinner, you’re gonna get fat. If you eat that salmon salad every day for dinner, you’re probably going to get thin. So it’s not about the calories. There is nothing to do with it, right? The minute you put your cookies into your mouth, the body responds with hormones and eventually tells your body to gain fat. When you eat the salmon, the instructions go into your body not to gain fat and maybe use it for other things like building up protein, building up bone, burning it as body heat giving you more energy to maybe want to go out and run around. The thing is that there is nothing the same. Those calories are not equally fattening. We have pretended for so long that calories are all the same and I think it’s because there is a lot of vested interest in trying to convince that all calories are the same. Therefore, you can eat cookies every day for dinner. It’s simply not true! 



Cause of obesity

The problem of obesity is not a problem of calories. It’s the problem of our body that is storing fat when we actually wanted to burn off that energy, right? So instead of storing body fat we want it to burn so that we have more energy to go out and run, to generate body heat to keep our brain functioning at a high level. So it’s really a distribution of energy problem; not a total calorie problem. That’s the important thing to understand. So then you have to say, “Well, what hormone is it that tells us what to do with our energy? Stored as fat or to burn it?”

Type 1 diabetes vs Type 2 diabetes
Well, insulin plays the main role. There are other ones, of course. Cortisol is also a major player but insulin is the main one. So as long as you understand that obesity is, in essence, a hormonal imbalance and not a caloric imbalance then you can focus on the key issue which is “How do I correct that hormonal imbalance?” Yeah, so insulin is a hormone that regulates the blood sugar and essentially that’s the blood glucose into the cells. Type 1 diabetes, so all of that – all of both side 1 and type 2, are characterised by high blood sugars. The reason in type 1 is that they have very low insulin level because the insulin levels are very low the glucose can’t get from the blood into the cells so it stays very high. Inside the cells are starving but outside there’s too much glucose. That is not the case in type 2 diabetes. In type 2 diabetes, you have something called insulin resistance

where if there is insulin then the cell, for whatever reason, does not let the the glucose inside. So the blood glucose stays high. Diabetes just refers to the high blood glucose. Type 1 is lack of insulin type 2 is an insulin resistance with actually high insulin not low. That’s the difference! Most people, about 95% of people, have type 2 diabetes. Though, both types are actually going up the type 2 diabetes is the one that’s really going up a lot. It is the one that is seen in older adults. It is the one seen in people who are generally overweight although people with normal weight can also have type 2 diabetes. Type 1 is the one that is classically thought of as presenting in childhood, usually very very skinny. So that’s the difference between the two.

Treating type 2 diabetes

Well, right now I think our current treatment for type 2 diabetes is almost entirely incorrect. We give people medication to bring down that blood glucose. But we actually don’t do anything for the problem. So the problem is not the high blood glucose. That is just the symptom. The problem is the insulin resistance. Because we have insulin resistance there is high blood glucose. But we treat what we see and not the actual problem. So because of the insulin resistance if we don’t treat it then it continues to get worse. The thing is that a lot of our treatments actually make people continue to gain weight. If the problem is that they weigh too much already and they’re gaining weight because of the treatments we give them it’s not likely that diabetes is going to get better. In fact, it’s going to get worse. That is exactly what we see. So over a period of 10 years or so people will typically go from one medication to two to three to insulin to more insulin to more insulin. So all that time the diabetes has never gotten better. It has only gotten worse. They tell you it is because that’s the way the diabetes works. It just gets worse. It’s like age, right? You can only can get older. That is actually not true at all! 

Type 2 diabetes is actually completely reversible and we have proved it over and over again. In fact, in our hearts we already know that type 2 diabetes is a reversible disease because you can find stories all over the place anywhere. If somebody loses 50 pounds, very often the diabetes will go away. They’ll take themselves off their medications and diabetes will go away! The blood sugars normalise. So we know that weight loss, in many cases, will reverse left type-2 diabetes. So it wasn’t that it’s a chronic and progressive disease. In fact, we focused on the wrong thing. We saw the high blood glucose, this is what I was talking about – that kind of old mentality – “ High blood glucose? Let me give you this pill!” But that’s not the problem. The problem is the obesity. Take care of the obesity and the type 2 diabetes will get better. You go to your doctor and instead of your doctor saying “Okay! We need to, really seriously, make you lose weight!”, what they do is give you a pill instead. Well, because they never took care of the root cause, which is the obesity, you will never get better. The reason they don’t take care of the obesity is because, again, they have this kind of flawed understanding of the cause of obesity. So they have done it so many times. They told people to cut their portions and exercise more. Nobody loses weight. Guess what? Everybody has done it. Nobody loses weight on these sort of diets. They have done it so often that they have given up on trying to get people to lose weight. So they just give a pill. 



But once you fix the obesity problem the type-2 diabetes goes away. That is what we do instead. When we see people with type 2 diabetes we say, “Well! Firstly, you don’t need medication. That’s only gonna band-aid the solution. What you need to do is lose weight and this is how you do it. You need to lower your insulin.” In most cases, it’s an insulin problem. If insulin is too high then we need to bring it down. The ways to bring it down are low carbohydrate diets and intermittent fasting. So that’s what we do. 

Dr. Fung’s recommendation for people with insulin resistance

Once you understand that the problem with obesity is too much insulin. Insulin resistance actually plays a key role because if you have it then it will keep your insulin levels very high, which will keep you from losing weight. So the question is what you can do to lower those insulin levels? In terms of the foods there are actually two key components to weight loss and everybody always, kind of, ignores one. So it comes down to two things. Basically what you eat and when you eat because you can’t ignore the question of frequency, right? So the question of what to eat is we more or less agree on that. So a lot of people, for example, understand that while eating a lot of white bread and white rice and sugar that it’s not really all that good for you and tends to be very fattening. So, of course, you need to cut those down. Those are at the highly refined carbohydrates and sugars. If you follow a relatively low carbohydrate diet and try to avoid processed foods then most people will agree on that. Yes, there are different variations but, for the most part, people understand mostly the same things. We have kind of gotten away a lot from this from this kind of low fat hysteria, which kind of followed from the calorie kind of misunderstanding. So if you remember, everything was about calories back in the 80s, right? That was the old thinking.  Therefore, fat was very high in calories and you shouldn’t eat it. And so everything was low fat, low fat and low fat! Then we realised that there are a lot of healthy foods that are high in fat. So olive oil, avocados, nuts, the whole Mediterranean diet really! There is everything that was just swimming in olive oil, right? Well, how can it be? So they got something called healthy fats and the thing about it is that that term kind of didn’t exist 20 years ago. All fat was bad! But now we realise that there’s a lot of fat that is actually very good because it’s not about the calories but it’s about the fact that these are unprocessed foods and they’re not high in carbohydrates. 

Carbohydrates refined, like bread and sugar, will stimulate insulin the most and therefore are much more fattening – calorie for calorie! That’s why if you eat grilled salmon with olive oil compared to brownies, the brownies are much more fattening because they stimulated it much more. One key is to go to a low carb high fat diet. But not all fats are the same either, right? You are trying to want to stick to the healthy fats because they’re kind of non processed. The other thing is the “when to eat”. The another thing, I think, that we’ve really gotten incorrect is that if you eat; almost all foods will stimulate insulin. Insulin tells our body, “Okay! So we are eating. Therefore, we want to store food energy. We don’t want to burn stored energy.” That is what body fat is. It is stored food energy. It tells us we need to store it. So if you eat six times a day then you’re gonna tell your body to “store fat! store fat! store fat!”. If from the minute you roll out of bed you start telling your body to store fat and all through that day you keep telling your body to store fat then what’s gonna happen? Well, you’re gonna gain weight because you just told your body to do so!

Fasting in history 

The key is not to eat all the time. If you look at studies from 1977, the average number of meals per day in America was 3. By 2005, it has gone up to close to 6. Back in the 50s, they were eating white bread and Oreos, right? But they were eating breakfast, lunch and dinner. No snacks! Now we go breakfast, snack, lunch, snack, dinner, snack. The thing is that we have never allowed our body the time in which we are not eating and in which we can actually pull some energy out instead of storing it. Right now, we keep eating all the time and we tell our bodies to store this food energy. We never are able to go the other way and pull it out. Well, that’s what fasting does. It gives your body a chance to use the energy that you stored. Guess what? There is nothing wrong with it.



Fasting – A math problem
Fasting is actually part of natural human evolution. The very term itself breakfast means you break your fast, which means you have to be fasting in order to break it. It’s a part of every single day. You need to balance those feeding periods and those fasting period if you’re gonna lose weight.

That’s the thing we have completely lost – that balance – instead of being, kind of, ten hours feeding and fourteen hours fasting or so in the 50s. Again,  if you imagine that you eat breakfast at 8:00 and dinner at 6:00 that’s about 10 hours of eating and 14 hours of fasting. During those 10 hours of eating you are storing energy and during those 14 hours you are pulling that stored energy. Oh, great! Perfect balance. Now, we go, the minute we wake up in the morning at 7:00. Somebody says, “Oh, you got to put bagels in your mouth or something.” You keep eating throughout the whole day until you go to bed. Well now you’ve got like 16 -18 hours of feeding and 6 hours of fasting. That’s it! The only time you’re not eating is when you’re sleeping. All that time you’re in an insulin dominant mode telling your body to store food energy. And guess what? That is what it does. So over the years, you just gain weight. We have to kind of move it back. Now, if you want to actually lose weight then you can extend those fasting periods. Instead of being 14 – 12 – 14 hours, you can extend it longer. You can extend it to kind of 18 hours – 20 hours – 24 hours, whatever you want. That’s the idea. There are two things – what to eat and when to eat – and the reason that log tides fail is that they completely ignore this question of “when to eat” and they just concentrate on “what to eat”. That’s only 50% of the battle .

Fasting and its variations

Fasting has lots of different variations. So there’s classic water – only fasting, which means that you won’t eat; you just drink water. There’s also fat fasting, which is where you only eat fat. What this refers to is the kind of recent phenomenon of bulletproof coffee, which is coffee with a lot of butter in it that is almost pure of fat. What you’re getting is a lot of calories but not a lot of insulin from the fat because the fat has very little insulin effect. Luring insulin is the key to losing weight – you can do very well. So that is a way that some people could have kind of hacked themselves so that they’re getting the calories while making it easier for them to fast, without getting the insulin effect, which is what is bad about it. It works very well for some people. Some people use bone broth for longer fast. Some people use tea with a bit of cream. Some people even allow up to 500 calories a day on that fasting day. So even on eating little bit of calories it will still work. So there’s all different variations from zero calories up to even 500 calories on that fasting day and they still work very well. So there’s all different variations and there’s all different timelines. 

The most common ones would be, for example, a 18 hour fast daily or six days a week kind of thing. 16 hours means that you eat an eight-hour sort of window, so if you say from 11 a.m. till 7 p.m. you eat. But outside of those periods, for the rest of the 16 hours, you don’t eat anything. Just water and that’s the time that you’re gonna allow your body to, kind of, pull the energy back out from what you ate that day, those eight hours. That’s something that when people will do most days. When you extend it to 20 or 24 hours, for example, you will go from lunch to lunch or dinner to dinner. So your eat lunch then you’ll skip dinner and breakfast and you’ll eat lunch again. That’s 24 hours and again some people might do that perhaps 2 – 3 times a week and then you can go to 36 hours, which is skipping the full day. You can even go up from there. Most people stick to the intermittent fast but you can do long fasts as well you can go 5 days – 7 days – 14 days. We rarely go above that, although some people like the challenge of going longer. We do that in our clinics but they are especially monitored. We monitor people but even then we rarely go above 7 to 14 days .



Fasting helps diabetics?
Diabetics, for example, cannot change their diet without seeing their physician because any change in diet, not just the fasting, will affect their blood sugars. The medication that they are prescribed are prescribed on what our expectation of their blood sugar is. So if we expect those blood sugars to come down with our diet then we have to reduce the medication in advance. So I do that for people but that’s something people have to be aware of and make sure their physician is on board with that.

But people do very well because if you don’t eat your blood sugars come down. Blood sugars come down then you don’t need to take your insulin. So we will reduce their insulin. As they lose weight, the diabetes gradually gets better which means that we can gradually cut them of off their medications. But, again, you have to do that in a safe manner. Monitoring is important, making sure that you feel well, making sure that you get the blood work and the supervision that is necessary.

Benefits of fasting

Well, there’s really a lot of benefits and this is the thing that people generally misunderstand about fasting. They think it’s something really really bad for you but, in fact, it seems to have a tremendous number of benefits or weight loss and type 2 diabetes are the most obvious. But people have noticed, for example, that they have a lot more mental clarity. Some people find that they actually have a lot more energy. Some people find that their concentration and their memory goes up. So there’s a lot of different things. In fact, if you look back at the history of fasting there’s the ancient Greeks, for example, who fasted not because they needed to lose weight as there was not much obesity back then, but they did it because they understood that it increased their mental capacity. If you think about it, if you have a big Thanksgiving meal it’s not like if your brain feels super active, right? You feel kind of sluggish, actually. All you want to do is sit down on the sofa and watch football because all that blood has to go into digestion. There’s nothing left. If you don’t need all that blood for digestion then maybe your brain can work a bit better. So the thing is that there’s so many things that people talk about it – in terms of prevention of cancer, people talk about  it in terms of Alzheimer’s disease  – there’s all kinds of theoretical benefits. 

Breaking fasting myth #1 – Muscle loss



There are a lot of people who worry about it. There are a lot of myths out there, for example, one is that it’s going to lead to muscle loss – that’s a common one – or that it’s gonna lead to starvation mode or it’s gonna lead to anorexia. So there’s all kinds of myths out there and these studies have been done. In terms of muscle loss, there is a period where your body does break down protein in order to provide glucose but what people don’t understand is that when you eat again you rebuild that protein. So when you look at studies of fasting you actually don’t see the same muscle breakdown or lean mass loss that you would see with, say, calorie reduction. So, caloric reduction, which has cut a few calories every day, doesn’t really work. It has actually much more effect to losing your lean mass like your muscle and so on. It’s much worse because people are ignoring the fact that your body will rebuild that. 

Breaking fasting myth #2 – Body shut down
Starvation mode is the idea that your body will slowly shut down. Again what’s ironic is that if you just are used to portion control, where you cut a few calories a day, your body will slow down but when you go to zero calories. Your body doesn’t because one it can’t go to zero calories and what you’re doing is actually you’re forcing your body not to slow down its metabolism because what it does is it shifts. It shifts from burning food to stored food so then your body’s like, “Okay, here are lots of body fat for you. Go burn it.” So then it’s like, “Hey, great!” So it continues to burn just the same. If you look up studies of fasting over four days, for example, at the end of the fourth day the resting metabolic rate or the basal metabolic rate is actually higher than it was at the beginning. Your metabolism does not go down. It goes up during fasting and that’s a huge, huge, huge advantage in weight loss. You cannot underestimate that because if you just try and cut your calories your body will slow down how many calories it burns because your body’s not really stupid. right? If you’re only taking 1,500 calories, say you originally took 2,000 calories you burn 2,000, now you go to 1,500 then your body almost immediately reduces your calorie expenditure to

1,500 because it doesn’t want to run a deficit. But if you go to “zero calories in” then your body simply switches fuel sources and says, “Oh, you are burning 2,000 calories. I’m going to give you 2,000 calories of body fat.” So it’s almost as if your body is eating breakfast, lunch and dinner of body fat. That’s why the metabolic rate doesn’t go down because it’s being fed. This is the thing. So the things that people are most worried about, ironically, are actually much better with fasting than with simple calorie restriction. 

Breaking fasting myth #3 – Anorexia Nervosa

The other thing that people talk about “Oh! It’s gonna cause anorexia.” It is a little silly because, first of all, anorexia is a psychiatric disease of body image. So if you have a 15 year old girl who is borderline anorexic then NO you should not be fasting, okay? That’s like common sense. But if you have a 65 year old man who weighs 300 pounds with type 2 diabetes then anorexia is not really what I’m worried about, okay? That man actually has a huge number of health problems that are going to kill him, that you need to treat. The remote possibility of that 65 year old 300-pound man developing anorexia nervosa – it is ridiculous, right? That’s like saying “Oh! Well, you know, Rebecca you shouldn’t wash your hands because you might develop obsessive-compulsive disorder.” It’s like NO. You’re just washing your hand, right? Don’t be ridiculous, right? But people are so ridiculous about fasting. There’s so many myths that are like so untrue. Even the other day I read this article about fasting – “Oh yeah. It’s such a bad idea. You’re gonna get anorexia.” Okay. But it’s like, so what you’re going to let this 300-pound man die of his diabetes because your are worried that he is gonna become anorexia nervosa? Don’t be so stuck and rigid and you’re thinking that you can’t use this. I’m not saying that everybody has to fast. It’s a therapeutic tool. If you don’t feel well then you should stop. If you start fasting and have real problems then don’t do it. It’s not for everybody. Nothing is for everybody. If you ended well then go ahead. 



The fasting hunger problem

In terms of hunger, for sure, people do get hungry. That’s not something that we can deny but what do they have to understand is that the hunger kind of comes as a wave. It kind of rises, rises, rises and then if you let it pass it’ll just go away and what we tell people to think about, kind of to visualise, is to imagine that you’ve just instructed your body to eat lunch of your body fat. Therefore, your hunger goes away. That’s really what we tell them to think about. Dinner is the same. The hunger is gonna go up but then have your glass of coffee or a cup of green tea or something and then it will pass. It doesn’t continuously build. The hunger doesn’t go up, up, up, up and up. What happens is that when lunchtime passes that wave fades and then it’s like, I get this all the time now, at 3 o’clock I’ll think “I wonder if I ate lunch today” because I really honestly don’t remember because I’m kind of so used to it that when I don’t eat the hunger passes and I just get on with what I’m doing. It’s like everything else. The first two weeks of doing it are going to be difficult. Right. It’s like exercise – you don’t go out and run a marathon the first time you go running and then say, “Oh! That was great.” You’re probably going to never do it again if you try to do that. Fasting is the same. It’s something that you have to kind of get your body used to and once you get used to it, it gets a lot easier because your body understands what it’s supposed to do. You understand what’s going to happen.

Period of adaptation 
The thing about the tiredness is that we tell people to do everything that they normally do because, again, what has happening is that you’re simply using the food that you stored away. That’s what body fat is. It’s food energy that you’ve stored away from yesterday, the day before or the week before, whatever it is. Now you’re simply pulling it out of storage and using it. It’s like a



refrigerator. You put that ham into the refrigerator and a couple days later you pull it out and eat it. Well, we’ve put this food energy into our body. Our body turns it into body fat and now we’re pulling it out and using it. Nothing wrong with that. In fact, that’s the way our bodies are designed to work and that’s the thing. So you shouldn’t feel tired. Now there is a period of adaptation. So there’s about a two-week period two to three week period where people will notice that they are not as energetic and that’s because your body hasn’t kind of made the adaptation to using that body fat. So we always tell people to give themselves at least, you know, two weeks to a month of doing it before you make a judgement. That’s what happens to people, right? They do one and it goes really poorly and then they say, “Wow! This is just terrible. This has got to be the worst thing ever.” It’s like running. You go out and the first time you run you do a marathon; your muscles are all sore  and you’re almost dead so you go “Wow! running is like the worst ever!!”  Oh no, nobody is really that foolish. But for some reason we think that with fasting. So you have to, kind of, take it slow. You have to understand what you’re doing. You have to know what to expect and then you can get through all these problems and that’s what our book is really about because when we went out I talked about this a lot and my co-author Jimmy Moore said, “Well, where can I read all about this ?” Nowhere nobody has anything about this and then he’s like “Okay. Then we should write a book about it,” because we want people to be able to read it and say “Oh, look they told me this is what’s going to happen.” 

With hunger, it’s very interesting because one of the things that we see people coming back at all the time is they say, “You know I think I thought I’d be really overwhelmed with hunger but the more I do it, the more I think my stomach is just shrinking,” and I say, “What do you mean?” He said “Well. Now I eat like a third of what I used to eat and feel completely full.” I’m like that’s great. If you’re eating a lot less and feeling full then now you’re working with your body to lose weight instead of against your body because with every other diet, which tries to restrict calories, everybody gets more hungry. They try to will themselves not to eat but that only lasts so far. Now you don’t have to will yourself not to eat, you’re actually just full. So your body is telling you not to eat. Why? Because you’ve been able to tap into those fat stores to supply the necessary calories that your body needs. So the hunger is very very interesting because it’s often exactly the opposite but there is a period of adaptation. So again it’s a huge advantage for keeping weight off. If you are able to eat much less than you used to eat and be full – that’s a huge advantage!

Reversing type 2 diabetes and weight loss

Weight comes down. The type 2 diabetes often follows right along and you can often reverse – you can take people off their medications. You can reverse a type 2 diabetes, reverse their pre-diabetes into kind of a normal range and this is something that has a lot of flexibility because if you decide that for the next week you’re going on vacation then you don’t want to fast then you don’t have to. But you can do more the next week to make up for it, right? So there is flexibility in terms of what to do and when to do it. You can choose when you want to do it and when you don’t want to do it. It’s totally up to you. You can do longer. You can do shorter. You can do more of them. You can do less of that. Totally up to you! 



Do we have to change our daily routine while fasting?
Again we tell people to do it exactly like what they would normally do and don’t change anything. Other than that kind of two-week period of adaptation where you’re getting kind of getting your body used to it, most people find that they actually have much more energy than they used to have. In fact, some people have so much they can’t even sleep. They are like saying “Oh, I’m sleeping like three hours at night and I’m feeling fine.” I’m like “Yeah! That’s all you need then,” because their body is kind of liberating this food energy so much that they have too much energy. So if you

normally exercise then go ahead like you normally work. In fact, doing it during working time is actually the easiest thing because you’re so busy doing other stuff and you don’t even notice that hunger because we all get that hunger at our accustomed eating time like lunch, dinner, breakfast for those we eat breakfast. So it will come kind of an anticipation but if you’re really busy and who hasn’t done this? – you just work right through it! It’s like nothing at all, right? Some people say “Oh, I’ll do it when I’m not at work.” I’m like that’s the worst time because if you’re just sitting around, you know, at home and your fridge is right there and your pantry is right there and you’re doing nothing else then you’re gonna think about “Hey! Maybe I should get something to eat!” or you’re watching TV and there’s all these food ads coming on or you’re watching Food Network then well you’re gonna think about it! Doing it at work is actually much much simpler than anything else. 

Problems with fasting 

Well there are lots of problems that do come up. Headache is very common but it often goes away. But the thing that you have to understand is that if you’re not feeling well then you have to stop because some people will get different problems and some of them will go away by themselves, most of them will, and some of them won’t. Everybody thinks that fasting for 24 hours is so unusual but we tell patients to do it all the time. When we tell people they’re going for a colonoscopy then they have to fast. When we tell people they’re going for surgery then they have to fast. When they come in and they’re sick with pneumonia they are fasting because we don’t give them anything to eat because they’re so sick. When you get sick with the flu and you can’t eat anything then your body is naturally making you fast. You just drink some chicken soup or something, right? So this sort of stuff happens all the time. It’s not an unnatural thing. 

People have to realise that, you know, lots of things can happen but you have to use a bit of common sense. Know what to understand but again if you’re feeling like really, really tired during a fast – and it happens time and again – and it’s not getting better then you should probably stop and see what else you can do to change it. Get some help. Talk to some people because it’s not normal. If you’re feeling pain or if you’re feeling unusual lethargy then don’t do it. Especially with the longer fast because some people will go with longer fast and they’re more powerful but there’s more risk with them. So, again, if you’re trying to do longer ones and you’re not feeling well then stop that. There’s nothing wrong with doing a shorter one and then taking a break and then doing it again, right? Again some people worry about doing too much of it but again I have treated many people and almost like 99% of time our problem is getting people to do it. Not fasting, right? So we don’t worry so much about people doing too much. But it is a worry. If your weight is too low then you shouldn’t be fasting. If your body mass index (we cut it off at 20) at 18.5 then it is considered underweight but if it’s under 20 then – no – I don’t recommend fasting at all! So there are certain people who shouldn’t fast like pregnant women, children and breastfeeding women. If you’re on medications then you need to get some supervision. But again, outside of that, if you are very overweight and you are feeling well then go ahead. Go ahead and do it.



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