5 Stages of Intermittent Fasting | Jason Fung

insulin resistance, diabetes, blood sugar, weight loss

Intermittent fasting can be divided into 5 stages, from feeding to post absorptive to gluconeogenesis to ketosis to protein conservation. Each stage is accompanied by different physiologic processes, so understanding the stages allows you to target the benefits. Check out my blog at

More Information:

The Obesity Code – Reviewing underlying physiology of weight loss and how low carb diets and fasting can help.

The Diabetes Code – Reviewing how type 2 diabetes is a reversible disease and dietary strategies.

The Cancer Code – Scientific exploration of how cancer develops –

Canada –

**Fasting Aids**
Pique Fasting Tea (recommended)

Fasting Community and Coaching:

YouTube Medical Lectures (for specialist physicians):

1. The Roots of the Obesity Epidemic –
2. Therapeutic Fasting – The Two Compartment Problem: ​​
3. Does Calorie Counting work? ​​
4. Two Big Lies of Type 2 Diabetes –
5. Reversing Type 2 Diabetes Naturally –
6. Insulin Toxicity – ​​
7. Saturated Fat – Friend or Foe?
8. Diet and Disease –
9. Dangers of Fructose –
10. Insulin Resistance –
11. Role of Hormones in Weight Loss –
12. The Obesity Code Lecture 1 –

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  • Pete G. says:

    72 hr fast and eating ketovore… down 76lbs in 4 months, and zero loose skin. Thank you Dr. Fung, and Dr. Berry!

  • Paul Purser says:

    Sept 2020 I read The Diabetes Code and started eating LCHF combined with a 36/12 fasting schedule, as recommended in the book. Within 2 weeks I was off my diabetic meds and now 8 months later I have lost 135 pounds. So many changes have happened since then, this information has been life changing. One of the most surprising was that I had to switch to an old pair of glasses because my eyesight improved.

    • Christine Kelly says:

      That’s awesome! Well done, I’m just starting out. I’m doing alternate day fasting, not sure if Jason Fung recommends it though…

    • TheRedPIll says:

      What does LCHF mean? Please indicate what the acronym means. Thank you.

    • Joie says:

      @TheRedPIll – LCHF means “low carb, high fat” – essentially, Keto (but, there are so many ‘variations’ on it)…guess you kind of have to experiment with yourself and see what works for you😊 Best of luck on your journey!💕😁

    • Joie says:

      @Christine Kelly – Dr Fung discusses ADF in his books, “The Obesity Code” and “The Complete Guide to Fasting”, as a viable fasting schedule (IIRC), so you should be fine with it, depending on your overall goals. Both books are wonderful, and *highly recommended* ! I have insulin issues😬🤪, so ADF is my preferred approach, fwiw, after an extended (>72 hrs) fast…hang in there, and DON’T GIVE UP! Even if you have a few “mis-fires” and have to stop/start a few times, just get back to it and keep going – you’ll get there, eventually!💕 I’m saying that as much for myself as for you, I suppose😢😊…it’s ‘easy’ to fall back into old patterns when something you’re trying doesn’t appear to be working. I’m sure you know what I mean – we’re all a constant work in progress! I find that what I do one week usually manifests itself the following week, so if I can just remind myself of that, it usually helps me push through the rough patches…cheers!🙏🏼❤️

    • Christine Kelly says:

      @Joie Good to know, thank you! We are indeed works in progress, I am getting past my food issues with daily prayer to God, which has been the best thing I’ve ever done. May this journey make us all more peaceful and powerful! 🌻

  • kelly swanson says:

    I have lost 112lbs so far doing fasting. I started on August 27, 2020 at 310lbs. Today May 15, 2021 I’m at 197lbs.

    • Leanne Lollypop 🍭 says:

      Well done Kelly 🙌🏼 go girl 👏😁

    • kelly swanson says:

      @Leanne Lollypop 🍭 thank you, but I’m a 57 year old man.

    • jason mcentire says:

      That is quite an accomplishment! That’s wonderful

    • Sven Holmgren says:

      That is great news! What lengths of fasting did you start with, and did you change once you got used to it? How did you feel throughout?

    • kelly swanson says:

      @Sven Holmgren I started 18/6 with no snacks. Then one meal a day. It depends how fast your body says you can go. Now 8 months later I do up to 2 week fasts but mostly no longer than 7 days. I feel great. And it not only curse obesity. It does wonders for over all health and well being. Physically, emotionally, financially and psychologically. You can’t go wrong.

  • Rocky Mtn Momma says:

    Last week I completed my 500th fast. I’m 46 years old, lost 42lbs so far, and feel great! I usually fast 23.5hrs each day and try to eat high fat/high protein and no sugar. I expect to continue with this way of life forever!

  • Sean Quinn says:

    Started fasting 1 Jan 2021. The first weeks were on a 18/6 regime where the feeding window was keto based. Then shifted to OMAD (one meal a day or 23/1). Did a few 48 and 72 hour fasts as well. Lost just over 90lbs in under 5 months and now weigh just over 200lbs.

    • Hoang Thai says:

      If I am doing 18/6 regime consistently ,am I ever going to reach ketogenesis with this fasting regime. Thank you

    • GOD420CRUSH 805 says:

      @Hoang Thai mixing it with keto diet you will

    • Rick James says:

      That’s amazing, losing 90lbz so quickly. I’m doing something similar to you, though my weight loss is a bit slower than yours. All good though, 👍, every bodies body is different, just need to enjoy the process.

    • San Cam says:

      Wow! Amazing, your schedule is what I am planning to do so hopefully I have similar results.😊

  • OmaBike says:

    When I was younger, I lost 90 pounds by eating every 2 or 3 days for several months. I never had loose skin, but I thought it was because I was so young. So the info on autophagy is interesting. Bookmarking this one.

  • leaF says:

    Why is there 200 dislikes? this information is so valuable it’s ridiculous.

  • Trex100 says:

    I’m 62 hours into a water-only fast at this moment. Feeling ok… These videos are super helpful for keeping me motivated. My goal is 100 hours. I really appreciate the work Dr. Fung has done. Thank you sir!

    • Ciaran Byrne says:

      Are you adding pink Himalayan salt, potassium chloride and bicarbonate of soda to your water? I have started mine today at 12:05 I’m going to do 72 hour water fast with some green teas included. I’m going to keep up my exercise too👍🙂. How long are you going for?

    • Trex100 says:

      @Ciaran Byrne Hi, no. I do not have any of that Himalayan salt. I am now up to about 90 hours. I have some bone broth simmering on the stove. When it is done (in about 6 hours) I will break my fast. During my fast I have been drinking water, coffee and taking a pinch of sea salt from time to time. Today is the first day that is truly easy for me. Now, I must say that I am not afraid of fasting. Good luck and good health to you Claran.

    • CrazyEggs says:

      @Trex100 Can you explain why you took so long fasting instead just stop at 48 hours once per weeek or 2? And how are you today?

    • Trex100 says:

      @CrazyEggs Hi crazy eggs. Since this post, I have done 80-100 hour fasts about 5 or 6 times. It has gotten progressively easier. I do it mostly to stay slim and to detox my body. My health is good. I like to fast for more than 48 hours just to stay in ketosis as long as possible.

  • ailín - more says:

    Dear Dr. Jason Fung:

    I’m so grateful to have followed your teaching on fasting, I’m 66 years old woman who weight 256 pounds, sick, tired, no energy, depress, could not walk short of breath, could not put my shoes on, I spent a lots of money on diet pills, pourer, diet programs to lose weight and nothing worked, since I started to watch your videos on obesity, diabetes and fasting. I have lost 43 pounds since February 15, 2021. I used to be 3X and now I’m size large, I have a lot of energy, no pain and I feel good about myself, and although my son lost 38 pounds, he weight 344 pounds, now he is down to 306 and he’s happy to do the OMAD fasting with me, thank you Dr. Jason Fung


    Maria Contreras

    • Debbie Wilson says:

      Hi Maria – it really is beautiful to read so many stories of weight loss, they are so inspirational. I’m 60 (and 2 months) and have just begun intermittent fasting. It is stories such as yours and the other people who take the time to write about their success stories that are truly inspirational, so from my heart, to everyone who takes the time to write, I send a big thank you 🙂

    • heythave says:

      No tortillas, tacos, rice, beans, and sodas will help during those times when you eat.

    • Sams Mom says:

      What an inspiration! I just started. I’m on my second week of OMAD. I actually didn’t eat today because I just didn’t think about it, which is weird for me. I’ve been doing the BBB&E for 8 days straight with OMAD and then one morning around 4AM I just had to have some other food. I took a day off and now I’m OK, but I’m wondering if I’ve totally messed everything up. I had wanted to go 30 days straight on the BBB&E.

  • Ram Velavarthi says:

    I’m doing OMAD at the moment and I reduced from 102 to 97kgs in one single week! I’m doing 5kms of a brisk walk in the morning every day! Planning to follow this routine for the next 5 weeks and come back and post the results! please wish me luck!

  • Kerri Kirk @ Adornament Designs says:

    I just did 36 hours and going strong! Stretching for 48!!!

  • Lara Ruth says:

    Day 7 water fast. Lost 10 pounds pure fat and 2.8 water. Going for 30 days. Thank you Dr Fung for educating the world on fasting. I’m saving my own life for free!

    • Harlan Sim says:

      Congrats on improving your health and hope you’ve kept the weight off.
      I just have my doubts on the breakdown of those numbers. I’m not an expert, nor have I fasted for that long. From the data I’ve seen, typically the ratio of fat to water weight lost should be reversed, 2lbs : 10lbs.

    • Julie Ellis says:

      How much did you weigh when you started, if you don’t mind my asking? I just started what I expect to be a 3 day fast but if I feel okay , I may extend it. Did you add salt?

    • Karlie S says:

      Any updates Lara? How did your fast go?

    • Gracie Freebush says:

      30 days on water only? Am I reading this correctly?

    • Troy Edwards says:

      Free? Technically, you’re saving money since you’re buying FAR less groceries 😉

  • Jason Fung says:

    Check out my thoughts on the Low Carb Diet – https://youtu.be/VwaIeWBk4TM

    • Ojas Cool Adventures says:

      Can you help me understand impact of insulin resistance/ PCOS and fasting?

    • Susan Malaika Bailey says:

      @Monica Saenz He is

    • vijay tv serials says:

      Sir i am from india already i was in conspitation . After intermittent fasting makes me worse. Pls suggest a relief from that immediately . Cant bear the pain

    • M D says:

      @Monica Saenz yes, he is a Nephrologist (Kidney/Renal specialist).

    • Continue Education says:

      Hi, been a fan for years. I have a very good question for you. I’m eating those miracles noodles made from glucomannan omad. It’s been 6 days & I’m in large ketosis. I’m not spiking insulin so my question is. If I’m only having this & staying in full ketosis, am I missing other components of a regular fast? Or is this close to the same? I couldn’t find much info on this & thought you would know.

  • louise bartels says:

    I started intermittent fasting the first of October and now do OMAD. I eat extremely low carb/high fat diet, go to gym and exercise. I have lost 20 lbs. I have lost brain fog, feel emotionally great, can almost run up a flight of stairs and I’m 66 yrs. old. Will keep this up until I reach my ideal weight. Thank you Dr. Fung!

    • Bleu Green says:

      Hi Louise,
      I’m considering intermittent fasting. And maybe two meals a day.
      This is something I haven’t tried before, and my fear is that the process will cause me to be too weak to work each day.
      I suffer from daily fatigue and brain fog, and I have breathing and sleeping problems, among others.
      So I’m actually inspired by your comment and I think I’m ready to give intermittent fasting and two meals a day a try!

    • Diane Olson says:

      I eat 2 pieces of liver when I feel tired it is great

  • Skins189lbs says:

    I’m an Uber driver and I was 3.5 days into a fast when my passangers wanted to stop at In N Out. They offered to buy my a burger. I was so tempted to take the free food, break my fast, get a protein style burger and keep it keto. I had every reason to justify doing it. But I resisted. They ate the food in my car too. It smelled so good

  • Boostisablast says:

    I’m watching this into a 48hour fast. Started at 211 in august and now I’m 155! Its so interesting to me and I’ve became hooked.

  • Elliott Waves says:

    Blood pressure was at 180/130, went on heart Meds, did a fast for 9 days, result was profound.. lost 25 pounds and had to come off of heart meds due to perfect blood pressure. Fasting really works

  • CattyBlu says:

    Thank you for your tremendous videos! They are so informative and inspiring! I am 50 hours into a 72 hour fast. Water and black coffee only to drink. One multivitamin and minerals tablet. Himilsyan salt and water 5-6 times a day. Walking 10,000 steps per day (just over 7kms). I feel amazing. Strong. The only uneasy thing is the “sucked in” feeling in my abdomen which is a bit annoying. I hope I’m in autophagy, hard to tell. I’m overweight by 30lbs (currently at 184), so the weight loss is a side benefit, but the health benefits feel great. Of course I’m making pizza for the kids at the moment, but I don’t feel hungry (lucky for them! 😂). Thanks for your videos. Prevention is better than cure!! 🎉

  • Dj Digital says:

    I’m a very young 59 year old who been fasting for years. During COVID-19 my weight was 192lbs. at 5’9 in height.
    Today I weight 130 after 2 years of fasting. I only eat once a day and at least one day a week l don’t eat.

  • Lisa Strong says:

    I am 62 and have been on intermittent fasting since February 2023. I’ve lost 70 lbs and changed my diet completely.

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