‘Can you have a normal blood sugar and still be insulin resistant?’

Ask Dr. Jason Fung

Why does my blood sugar rise when fasting? Can you have a normal blood sugar and still be insulin resistant? And can resistant starch be eaten on a keto or low-carb diet?

It’s time for this week’s Q&A about intermittent fasting and low carb with Dr. Jason Fung:

Why does my blood sugar rise when fasting?

When fasting, I notice my blood sugar rises instead of dropping. Why is this and how do I correct it?


It’s due to the counter-regulatory surge. Normally, as insulin falls, other hormones go up. As these run counter to insulin, they are called the ‘counter-regulatory’ hormones. These include activation of the sympathetic nervous system, noradrenalin and growth hormone. The normal purpose of these hormones is to increase blood glucose. During fasting, insulin drops and these hormones go up, so blood glucose may go up instead of down.

Is this a bad thing? No. Not at all. After all, if you are fasting, where did this glucose come from? It could only have come from one place – your own body stores. So your body is liberating this stored glucose for you to burn during fasting. A completely normal phenomenon.

See posts on the Dawn Phenomenon for explanation.

Dr. Jason Fung

Can you have normal blood sugar and still be insulin resistant?

Hello Dr. Fung,

Can one have normal HbA1c and be insulin resistant?

Thank you,

Yes. There are many different manifestations of insulin resistance, only one of which is elevated HbA1c. I prefer to call these manifestations of ‘hyperinsulinemia’ instead of insulin resistance. Hyperinsulinemia causes all of the facets of the metabolic syndrome including high blood pressure, high triglycerides and low HDL, increased abdominal obesity and high blood glucose (which can be measured by elevated A1C). Sometimes hyperinsulinemia is manifested by abdominal obesity and other time, elevated blood glucose (type 2 diabetes), but the overall problem is the same.

By calling it hyperinsulinemia rather than insulin resistance, the solution becomes obvious. If the problem is too much insulin, then lower it. How? LCHF diets and intermittent fasting.

Dr. Jason Fung

Resistant starch on keto or low carb?

Can resistant starch be eaten on a keto or low-carb diet?


The data on resistant starch is very preliminary but extremely interesting. Resistant starch are starches that are not absorbed by the body and therefore act more like fibre than starch. Potatos that are cooked and then cooled, for example, may develop resistant starch, which may then not be as bad as regular starch in terms of blood glucose. However, there are no firm answers yet.

Dr. Jason Fung



Intermittent Fasting for Beginners

Earlier Q&A

Intermittent Fasting Q&A

Q&A videos

Top Dr. Fung videos

More with Dr. Fung

Dr. Fung has his own blog at intensivedietarymanagement.com. 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. Mina
    I lost a lot of hair on LCHF and intermittent fasting. :(
    Replies: #2, #12
  2. Peter
    Mina, it should be temporary - see article on this site.

    I am seeing a consistent trend with intermittent fasting, that of weight gain. It happens almost immediately after the fasting ends. Takes a couple of days with longer fasts but always ends up higher than before the fast. It is definitely not over feeding as I have been measuring calories and carbs and ensuring these are normal.
    Anyone else experienced this or know what is happening ?

  3. Mrs rohini
    Hlo sir , my name is rohini and my que is that my daughter is 15 years old and she is dibetic from last 3 years sir she is talking insulin humolog in 3 tyms a day and lantus too at bed tym still her blood suger is not in control 250.. 300 is fasting range after meal 380..240 what cn i do for my daughter to control her blood suger sir plz help me thanku
  4. N D NAIR
    Having insulin HIMSSULIN 30/70 daily morning...evening 25 mg for months together is that the sugar level is 204/214.
    Sbold i take tablet also jn this case.
    If so which tablets is good to reduce.the level
    Instead odf sugar i take sugar free in tea n coffee.
    Suggest me whether should i go fir auyurvedic medicine fir ontrol..???.
  5. Mina
    Peter, please define temporary. I've been loosing hair for 3 years now since I started LCHF and fasting. Is that temporary?
    Reply: #9
  6. Ericha
    Mina, I too, have lost 1/3 of my hair since starting a Ketogenic diet 9 months ago, with no signs, that it is slowing. (luckily I started with extremely thick hair), but I am now taking 100mg of Spironolactone 2x/day and applying g 5% Minodoxil foam to scalp 2x/day as well. Although I know this is only damage approach, (I am scared and desperate), I need to get to the root cause of this… which I believe is hormone imbalance. Just don't know who to turn to for help with this. (Primary, endocrinologist, and, OBGYN=useless)
    If anyone has any ideas, I am all ears!
  7. CASS
    I too am Type 2 uncontrolled, 200s, controlled a goal quite unachievable for me, too many variable health plan codes, now in the donut hole. Increasing insulin is ineffective.

    But hair wise:
    What works for me is Hair Regeneration Tea 2Xs daily, sold on Amazon.
    I also take Biotin 1000mg daily. This I have been doing for 1 year. I now have hair from shoulder to almost waist length this year.

    You can actually see the spurts in your hair growth on a daily basis, if you start out with trimmed ends. You can see the length growing beyond the trim, almost on a daily basis.

    My only problem is that my hair is thin in the crown. I have not worked that out yet. I noticed my beautician gives me heat treatments. So 2xs a week before I go to sleep I put a heating pad on the top of my head for 10 minutes.

    I think it is what we put in our bodies is what stunts our hair growth because when we die our hair still grows...

    I'm also giving my beautician a rest and saving money, but not enough to afford my vgo insulin therapy which helped me reach my am goal of glucose 80 and afternoon glucose 75.

  8. CASS
    Cass...Actually I left out a zero. That is Biotin 10,000 mg daily.
  9. Peter
    Mina, That does not sound normal. I believe temporary would be < 6months. You could have another problem going on there. Suggest you talk to a doctor.
  10. M. Martin
    This is a bit late but......... CASS ! hair grows from the roots, not the tip. Also it does not continue to grow after death. That is a well known myth. What happens is that the skin dehydrates and shrinks and that makes hair look longer than it is.
  11. Mamma
    My daughter is 16 and hasn't gotten her periods yet so we went to get a test. They kept telling us her blood sugar was in the perfect range but then did an insulin test and got 10iul/ml. How can her sugar be low but her insulin be in the slightly high rate.

    Is this due to her pancreas sending out insulin to break down the blood sugar (which then looks good) but meanwhile the insulin remains high ready to break down her next meal. They have given her metformin.

    Something like this happens to some people after Covid-19. I mention that because it is a stress response. So is changing eating habits ETC

    This may be part of the issue. this is a response nearly 5 years later but could help some one today

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