How permanent is the effect of intermittent fasting on insulin resistance?

Ask Dr. Jason Fung

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

  • How permanent is the effect of intermittent fasting on insulin resistance?
  • Does whey protein supplements help lower blood sugars?

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:

Fasting and insulin resistance

Dr Fung,
I have a few questions:

1. How permanent is the IF on the insulin resistance? After you lower the insulin resistance through a regimen of fasting, is it sustainable or you have to do it for life. As you mentioned, most weight loss diet are not reversible. So I wonder whether IF is sustainable.

2. In this study, it is mentioned that whey protein helps to lower blood sugar. For me, I take Whey after a gym regimen to help to build muscles. I am TD2. Is it harmful to take whey (not excessive – just about one spoonful provided by the Whey protein can).

3. What about Monk Fruit (natural – not processed). Is it OK to drink that or mix it with your drink?

Dr. Jason Fung:

1. It is not permanent. It’s like taking a bath. You can’t do it once and expect to be clean forevere.
2. I don’t recommend it. Stick to real food.
3. No.


Dr. Fung, thanks for the reply to previous questions, now have one about baby aspirin. I’ve been taking a daily baby aspirin in addition to all the oils for blood lubricity, and with all the bad press I’ve been reading lately I’m beginning to question the wisdom of that. I’m thinking the oils I’m taking : fish oils, avocado oils, olive oils, Vit E in tocotrienol form, and Vit. D’s, are enough to keep blood lubed up plenty good. Question is do I really need the baby aspirin. I know from your book “The Obesity Code” that you don’t seem to hot on the idea of aspirin. Whats the verdict?
1. Does aspirin artifically stimulate insulin?
2. Is aspirin a good thing to be taking regularly to help prevent heart attacks?
3. Other then use for a say, monthly headache is aspirin something a person wants in their diet?

Thanx in advance Doc !

Dr. Jason Fung:

1. No
2. No. Only in secondary prevention. The recommendation that everybody of the age of 60 take an aspirin a day is old and has since been retracted. It is a drug and has use in specific patient groups, not everybody willy-nilly.
3. No.

Intolerance to dairy and fasting tricks

Hi Dr Fung – thank you for your reply to my previous questions.
I’m now on Day 3 of my fast and feel good.
I introduced double cream (15mls) to each of my 3 coffees today, and it is becoming clear that I am intolerant to dairy products as my skin has already deteriorated after improving over the first 2 days of the fast. So:
1) Could I substitute canned coconut milk for the double cream? (15mls / serving x 3)
2) Are micronutrients stored within fat cells in the body. If not, how do you maintain electrolyte balance whilst fasting?
3) Would taking 2 tbsps raw organic apple cider vinegar daily be a good idea whilst fasting?
4) You suggested alternate day fasting at the end of a fast. – would this be a water fast or 500 calories as suggested by Dr Krista Varady in The Every Other Day Diet?


Dr. Jason Fung:

1. Yes. Try coconut cream instead of coconut milk. It’s delicious.
2. A general multi-vitamin supplement for extended fasts.
3. Yes
4. Either works.



Intermittent Fasting for Beginners

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The Obesity Code

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