How much should you fast once type 2 diabetes is reversed?

Ask Dr. Jason Fung

There are tons of questions about intermittent fasting, like these:

  • Does coffee when fasting affect insulin resistance and adrenal fatigue?
  • How much protein should one eat per day?
  • How much should one fast once they have reversed their type 2 diabetes?

Dr. Jason Fung is one of the world’s leading experts on fasting for weight loss or diabetes reversal. Here are a his answers to those questions and more:

Coffee and adrenal fatigue

I drink coffee, it helps with my fast, two cups per day. I watched a video on Diet Doctor with Dr. Michael Fox who says that coffee raises insulin. He also lost weight after he stopped drinking coffee. There is also a ketogenic lady named Stephanie Person who says coffee damages the adrenal glands. I’m confused. Is coffee healthy or not because it has a lot of pros and cons and it will interfere with my fast?


If you are getting good results with coffee during fasts, then continue. I doubt very much that coffee damages the adrenals, otherwise 9 out of 10 adults would have adrenal damage. Of course, as the old saying goes, “the dose makes the poison.” Drinking a cup of coffee is not necessarily the same as drinking a pot. Also, people have different genetic susceptibilities to caffeine. Therefore, the key is to understand how coffee affects you. For most people, one to two cups per day is perfectly benign.

Dr. Jason Fung

How much protein should I eat per day?

I understand that I need healthy fat to replace the carbohydrates. However, I want to make sure I’m also eating the right amount of protein. Is it so many grams per kilogram?


You can learn more about protein requirements and recommendations in Diet Doctor’s guides on protein intake.

Dr. Jason Fung

How much should one fast once type 2 diabetes is reversed?

I realize that everyone is different but for those of us doing shorter daily fasts what do you recommend for maintenance once we have reversed type 2 diabetes?


This answer will differ between individuals. I typically advise starting with two 24-hour fasts per week, or if you prefer longer ones, perhaps a 5-day fast per month. You can learn more in Diet Doctor’s guides to intermittent fasting and time restricted eating.

Dr. Jason Fung



Intermittent Fasting for Beginners

Earlier Q&A sessions with Dr. Fung:

Many more questions and answers:

Intermittent Fasting Q&A

Q&A videos

  • Is low carb bad for exercise?
  • Is low carb bad for the kidneys?
  • Everything in moderation?
  • Is low carb an extreme diet?
    Is low carb bad for the environment?
    Are there potential dangers with a low-carb diet?
  • Women's questions introduction
    What is the main benefit of low carb?
  • Does the brain need carbohydrates?
  • Can low carb and keto help with PMS?
  • Is low carb bad for gut bacteria?
  • Why is low carb important to you?
  • Can low carb make menopause easier?
  • Is low carb bad for the thyroid?
  • Is there a link between low carb and eating disorders?
  • Can you get depressed on low carb?
  • Is saturated fat bad?
  • Can fasting be problematic for women?
  • How do you maximize your health?
  • Do you need more carbs when breastfeeding?
  • Can exercise be problematic for women?
  • Isn't weight loss all about counting calories?

Top Jason Fung videos

  • Diet Doctor Podcast #64 with Jason Fung
  • Part 8 of Dr. Jason Fung's diabetes course
    The essential problem with type 2 diabetes

More with Dr. Fung

Dr. Fung has his own blog at He is also active on Twitter.

His book The Obesity Code is available on Amazon.

The Obesity Code

His new book, The Complete Guide to Fasting is also available on Amazon.



  1. Barb
    I am doing a 5 day fast. After the first 24 hours I have become extremely cold. I'm finding it hard to get warm no matter how I bundle up. Is this normal or a sign of slowing metabolism?
    Reply: #3
  2. RF121
    Everyone is different but cold extremities while fasting is normal.
  3. Apicius
    I discovered that soaking in a tub with magnesium bath salts does wonders for me when fasting. It warms me up to the core and the bath salts provide soothing feeling afterwards.
  4. Srinath
    I've been successfully fasting and lost 90+ lbs and even found it easier and more freeing. My longest was 19 and 3/4 days Nov 24-Dec 14 2016. However now @ 5' 9.5" male and 146 lbs, I am running into an issue where I am shivering and generally pretty miserable. I want to get to the single digits and have no discernible sub cutaneous fat. So I do want to fast up to 13 days (planned out eating days for the next 2 months and there is - 2 13 dayers). Can I eat mayo - all calories from fat, mustard (only vinegar and mustard) hot sauce - only red pepper and vinegar, and pepperoncini peppers, 3 of those have 1 gm carb, I barely eat 1 a day mixed with above 3 ingredients. I also need to eat salt and lemon (acid) as well as suppliments K, Ca, mg, zn, B complex etc past the 4-5 day mark right ? else I find I cramp up badly.

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