5 Stages of Intermittent Fasting | Jason Fung

today i'm going to talk about the five stages of fasting and what happens in our bodies during each of those stages so you can target your fasting schedule for what you want and stick around to the end i'm going to share gosta's story and how he was able to use the fasting to lose over a hundred pounds and get healthier [Music] fasting can be divided into five stages and this was done in the sixties through the nineties by dr george cahill who did all the classic studies he was a professor of medicine at harvard medical school and most medical textbooks still carry much of his teaching it was described in his article called fuel metabolism in starvation he divided these five stages of fasting according to where the body got its glucose from the body has two main sources of fuel it can use glucose which is a type of carbohydrate or it can use fat which is a molecule called the triglyceride and that's often stored in the fat cell which is called the adipocyte most cells of the body can use either glucose or fat the main exception being the brain which cannot use triglycerides for energy but most of the other cells like the liver and the muscles and the heart and the kidneys they can use either glucose or they can use triglycerides sort of like a hybrid car can use gas or electricity that's the same as a cell the body also stores energy in two main forms it can store glucose or fat so glucose is stored mostly in the liver and it's stored as a molecule called glycogen which are long chains of glucose molecules and it's very easy for the body to link all these glucose molecules up and when it needs to it simply takes that glycogen chops it back up into little molecules of glucose and sends it back out into the blood if it still needs energy and there's not enough of the glycogen then it relies on fat or triglyceride it's a little harder to get to but it takes the fat from the fat cells goes to the liver where it breaks down this triglyceride into three fatty acid chains as well as a glycerol backbone and the triglycerides can be used directly by most cells of the body for energy and the glycerol can be changed into glucose which supplies energy for the brain in stage one of the five stages dr cahill called this the feeding stage and this lasts from zero to about four hours after a meal during that time there's usually a lot of glucose around because people are eating a mixture of carbohydrates proteins and fats and when there's plenty of glucose all the cells of the body are using glucose as their main source of energy there are two main nutrient sensors in the body insulin and a molecule called mtor and when the body senses that you have carbohydrates and protein then these nutrient sensors go up and the body gets the message that it should start storing some of this energy for later on when there might not be any food available so it's going to store that glucose in the liver as glycogen and the body fat is also going to take the triglycerides in stage two of fasting dr cahill called this the post-absorptive stage which lasts from 4 to 16 hours during this time the body is really digesting the energy that is just taken insulin and mtor start to fall and most of the cells are still using glucose but not necessarily from the food because that's already been packed up away in the liver but coming from that storage site in the liver the the liver is now taking the glycogen breaking it back up into glucose and sending it back on average the liver can store about 20 to 24 hours worth of glucose to supply energy for the whole body this of course depends on what you eat if you're eating a very very low carbohydrate diet such as a ketogenic diet of course then there simply is no glucose available and the body is using ketones there's a lot of diseases that are associated with high insulin things such as heart disease stroke alzheimer's cancer type 2 diabetes high blood pressure high cholesterol and gout and making sure that you have a daily period in this post-absorptive state where you're going to allow those insulin levels to fall is really important because those diseases that are associated with high insulin are going to benefit from this period of low insulin the other thing insulin does is it tends to cause salt and water retention at the level of the kidney so during this lower level of insulin you're going to be able to release some of the salt in the water which means they're going to have a lot less bloating a lot less swelling and also your blood pressure tends to go down at the same time that insulin is going down other hormones are going up and these are called together called the counter regulatory hormones because they run counter of insulin insulin goes down and these go up and the main hormones here are cortisol the sympathetic nervous system noradrenaline is a prime hormone of that category and growth hormone and these are going to tell the body to start getting fuel from its storage sites from the liver to sugar and from the body fat and push it out and put that energy back out into the blood from storage sites and the metabolic rate is going to speed up a little bit too because the increased cortisol and sympathetic nervous system are actually going to energize the system while the growth hormone is going to make sure that there's plenty of growth available to build up whatever is necessary in stage three dr cahill called this stage gluconeogenesis which lasts from about 16 to 30 hours at this stage the glycogen in the liver which is the stored sugar is starting to run out and we haven't quite switched over into fat metabolism completely so there's this intermediate stage where the body is going to generate the glucose from protein that's what the word gluconeogenesis means it means the production of new glucose predominantly from protein this sounds pretty bad a lot of people are like wow you're breaking down protein that's going to take a toll on the body but that's not quite true this is likely the stage where we're seeing a lot of autophagy dr osumi the 2016 nobel laureate who won for his work on autophagy called it the body's intracellular recycling system what fasting does is it stimulates the breakdown of these subcellular parts which are often proteins and doing this achieves two things one it gets rid of all those old junky pieces of cellular machinery that are just not working that well and two it can take those amino acids and rebuild them into what's necessary and the process of breaking down old junkie parts and replacing them with newer better parts is actually good it's regeneration or rejuvenation the body is going to sense what is necessary to be rebuilt and going to rebuild it better but what is not necessary is not going to be rebuilt and this is likely why we don't see the problems with the excess skin that other weight loss programs seem to have when you do fasting you have this period of autophagy of gluconeogenesis where proteins are getting broken down and that's proteins like the excess skin and excess connective tissue and blood vessels that are simply not needed anymore and you don't get that if you don't have this period of fasting also people who are overweight and trying to lose weight typically have more protein than needed somewhere between 20 to 50 percent excess protein so in addition to losing the body fat you also need to lose that extra protein the main regulator of autophagy is mtor which is very sensitive to amino acids in the diet so if you're trying to target autophagy for the process of rejuvenation or looking or feeling younger then you might want to stick to a cleaner fast one without say bone broth and other things and stick to a water only or maybe some just herbal teas and green teas during your fasting stage four of fasting dr cahill called ketosis the brain is using glucose as its main source of energy but by this point which is more than two days into the fast there's not enough glucose coming from the glycerol so there's a little bit of ongoing breakdown of protein but in order to supply energy for the brain the liver takes the triglycerides from the body fat and turns it into ketones which now can cross the blood-brain barrier and feed the brain and it supplies up to 70 percent of the energy that the brain needs so people feel energetic and some people actually think that the brain metabolizes the ketones better so that it might actually give you a bit better performance concentration memory some people feel that it might also be necessary in the treatment of epilepsy to get this ketosis because it's a more efficient fuel for the brain in stage five of fasting you get into the protein conservation stage and this is when you're going more than six or seven days into your fast and you're getting into a rhythm where you're supplying almost all the energy that you need from your own stores of body fat you get into a cycle where you're only burning a little bit of protein from the gluconeogenesis but most of the energy from the rest of the body as well as most of the brain now is derived from fat interestingly enough this is the stage where hunger really starts to disappear and it's not clear whether it's the ketosis or what it feels like but when you measure hormones like gorelin the hunger hormone it really starts to drop and it's because your body is feeding itself from its own body fat that's the secret to how these people did 30 60 day fast people who go on hunger strikes people often wonder hey how can you do that aren't you hungry all the time and the truth is that they actually are not because they've gotten through into this protein conservation stage so those are the five stages of fasting and you can see which one suits you and suits the goals that you have for yourself and you can try different ones to see how they are for you mix them up and that's how you're going to lose weight and get healthier like gosta gosta was 63 years old and he had unfortunately gained a lot of weight it took a visit to the emergency room to make him very serious about getting healthy again his doctor recommended surgery for him but instead he wanted to try and lose weight so he went to the fastingmethod.com read through all the material and decided that his schedule was going to be four days he would eat and three days he would do water only fast he had a bit of tea a bit of coffee he had a bit of a refeed and then he would also increase his exercise so he is able to get into the gluconeogenesis stage where he's going to lower his uh insulin levels increases counter regulatory hormones and then activate autophagy as well he made sure to take advantage of the increased energy as well as the increased growth hormone and he did six days a week of walking about 10 kilometers as well as qigong and stretching and also strength training one to three times per week he took a rest day once a week and the results where he lost over a hundred pounds his waist to hip ratio goal was reached he remains strong and he went from having trouble even walking one flight of stairs to running up seven flights of stairs that's amazing acosta you did amazing thanks for watching if you learned something maybe share with your friends you might be able to help them too and if you enjoyed it if you could do me a favor and just hit that like button so that people will see that would really be a much appreciated thanks so much and i'll see you next week

Channel: Jason Fung

Views: 1,984,799

Keywords: fasting, intermittent fasting, jason fung, dr jason fung, stages of fasting, fasting weight loss, fasting benefits, fasting diet, fasting science, autophagy, Ketosis

Id: T7o_hF1XB84

Length: 14min 27sec (867 seconds)

Published: Sun May 09 2021

Reddit Comments

[u/mohishunder]

I'm learning a lot from the recent videos on Dr. Fung's channel - beyond what I remember from his books or the original blog.

In particular, it seems that longer fasts (3-7 days) may be significantly more beneficial than multiple shorter fasts.