Intermittent fasting — the best diet for type 2 diabetes?

October 11 2018 by in Dr. Jason Fung, Intermittent fasting, New study
Alarm clock with bells on the plate with fork and knife, lunch time concept, top view with copy space

Type 2 diabetes was once thought to be a chronic disease that could never be cured. You can start medications to control it, but those medications will be with you for life.

Now we know better. As Dr. Jason Fung has said, “People are focused on giving drugs to type 2 diabetes, but it is a dietary disease.”

He and his team at Intensive Dietary Management Program set out to prove that they can do better than drugs. They recently published a case report of three men with type 2 diabetes who were able to completely stop their insulin and most of the oral drugs while still improving their diabetes control.

BMJ: Therapeutic use of intermittent fasting for people with type 2 diabetes as an alternative to insulin

How did they do it? Intermittent fasting.

The subjects fasted for 24 hours three to four days per week, going from dinner to dinner without food, while eating lunch and dinner on the other days. They lost between 10 and 18% body weight and between 10 and 22% from their waist circumferences.

But here is the amazing part.

Starting from a daily average of 70 units of insulin, they safely stopped their insulin as quickly as five days into the protocol, with the longest taking only 18 days. That is a dramatic result!

Importantly, they were very closely monitored by the team at IDM. Fasting while taking diabetes medications can increase the risk of hypoglycemia, a potentially life-threatening lowering of blood glucose. Thus the warning that people should not try this without being monitored by an experienced healthcare provider.

When done correctly, however, intermittent fasting combined with a low carb diet may be the best treatment of type 2 diabetes that we have ever seen.

Thanks for reading,
Bret Scher, MD FACC

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36 comments

  1. 1
    bill
    October 11 2018
    The title of the report, "Therapeutic use of intermittent fasting for people with type 2 diabetes as an alternative to insulin"
    is misleading. If you read the paper, the case for
    fasting being the effective component was confounded by the use
    of a low carbohydrate diet. They cannot conclude that fasting caused
    the changes they observed.
  2. 2
    valerie
    October 12 2018
    How can you say it is "the best" diet when no other diet was tested?
  3. 3
    Rebecca
    October 12 2018
    What about the ADA diet 1000s of us T2 diabetics have been prescribed. Low calarie, low fat, most cal. from carbs... That got more meds more issues not well. 8 weeks on Intermittent Fasting and LCHF has 30 pounds gone and 4 meds gone out of my life. The crowd is educating themselves and taking action... Powerful.
  4. 4
    Peter
    October 17 2018
    I used intermittent fasting and a ketogenic diet to reverse my type 2 diabetes three years ago. My A1C is 5.5 from an 11.5 at diagnosis. Diet doctor and dr. Fung have been a life saver and true pioneers in helping people empower themselves from an outdated ineffective form of treatment.
    Reply: #30
  5. 5
    Jared
    October 17 2018
    I'm interested in the language of "Reversed" vs. "well controlled."

    To me, reversed would mean that if you gave these subjects a glucose tolerance test, they'd have non-diabetic blood glucose levels at the end of the test. Is that what is happening?

    Either way, this is obviously amazing and should be screamed from the mountain tops.

    Reply: #25
  6. 6
    Mario
    October 17 2018
    I only follow the low carb diet ( 30 and 20 gr per day) for 6 months and the results are very good I stopped using Insulin glargine 18 units every day plus 10 mg Dapagliflozin plus metformin 850 mg x 3 per day. And despite the medications, my Hbc was always 7 or higher. Now my Hbc is 6 my glycemic levels in the morning are 95mg/dl and 2 hours postprandial the higher has been 110 the average is 97. I stop using all the medications 5 months ago. ca we call this Diabetes reversal ? Of course yes.
  7. 7
    Susannah Shoaf
    October 17 2018
    I am currently using intermittent fasting and a ketogenic diet to reverse my type 2 diabetes for the last 7 months. I was first diagnosed 1/2017. My A1C is 6.0 from an 12.1 at diagnosis. LCHF diet is saving my whole immediate family's life. Reading the Obesity Code and listening to Dr. Fung has been eye opening. Sugar is evil. I'm using 1/4th the metformin and monitoring my fasting blood sugar daily. I'm almost off metformin!! It works!!
  8. 8
    Debra Neese
    October 17 2018
    I am Hypoglycemic and have boughts of low blood sugar attacks frequently. Yet I am also Pre-diabetic (3) yr's ago and probably diabetic by now. Anyway, I've tried Keto and get quiet constipated. I want to do fasting but my doc says no because of low blood sugar. I also have hypothyroidism and Sjorgens disease.
    What's the best diet for me? I wish I didn't have to eat, its a pain. I want to fast simply because of its convenience. Can you help me please.
    Thank you Debra
    Reply: #10
  9. 9
    Darren
    October 17 2018
    After four months of being on the keto diet and doing one meal a day i have lost 40lbs. And my A1c went from 9.9 to 5.4 and my daily glucose levels range from 80-100. I know it works for me
  10. 10
    Reply to comment #8 by Debra Neese
    Michael
    October 17 2018
    I have found that constipation in KETO is often a result of your macros not being in sync. Make sure you keep your fat intake up. 75% fat, 20 % protein, 5% carb. My fitness pal app is a good macro calculator to use.
    Reply: #26
  11. 11
    Joanne josephsen
    October 17 2018
    Love fasting with Keto. Been Keto 4 years and fasting for 2 years.
  12. 12
    Mark
    October 17 2018
    I started this Keto journey in June 2018 and dropped weight as well as dropping my A1C levels. I went from 7.2 to 5.8 and my doc still has me on twice a day metformin and 1 statin. Originally he had me at 4 times a day metformin!
    I also told him about doing IF but he said that is not good for people with type 2, as that will increase your insulin levels. (I don't think he gets it and just makes money from the pill people). Anyway next doc appt. is in November so I am hoping to be at the so called 5.6 A1C that is considered not Diabetic. Anyone ever hear of your GP telling you Fasting is bad? Currently I do IF two days out of the week and feel fine.
    Reply: #36
  13. 13
    Belinda Preece
    October 17 2018
    Our GP is keto blind, fasting blind and although we sent him links to Dr's Eric Westman and Jason Fung, he has yet to check them out and educate himself.
  14. 14
    Maureen S
    October 17 2018
    My A1c has dropped from 9 to 6 doing low carb/keto. Another appt at the end of October will see if it has dropped further. Thinking it will. I do a 16/8 IF but find it impossible to do a 24 fast, let alone, 3 or 4 days a week. I just don't see why this would be the only way to recover. Or suggesting/telling people, this is the only way. I am having great success doing what I am doing.
  15. 15
    Susan
    October 17 2018
    Mark, I have found that fasting makes my levels increase. I measure my bg at around 7.30am having eaten nothing from around 8pm and it will be over 7. I check hourly from then on and it rises steadily to anything between 9 and 11. Once I have something to eat, it starts to fall. I guess it’s an extension of the ‘dawn phenomenon’. So your doctor isn’t completely wrong. I think it’s down to individuals as to whether fasting is suitable or not.
  16. 16
    Paul
    October 17 2018
    I’ve been low carb since November 2016 and my sugar levels were down to high normal by the end of December 2016. I stopped taking Metformin and my sugar levels remained normal. I also stopped taking Cholesterol lowering tablets. In May this year I stopped taking blood pressure tablets and my blood pressure remained at high normal and became more regular and consistent.

    The only thing that I am still struggling with, is my weight which although initially dropped as risen a little, mainly due to holidays 😎.

    I’ve might try this intermittently fasting to see if it reduces waistline.

  17. 17
    Heidi
    October 17 2018
    For those suffering from constipation, google ‘linseed ‘ or ‘flaxseed’ bread. This is low carb/keto and works like a charm - just remember to drink sufficient water to help it move along.
    Reply: #18
  18. 18
    Reply to comment #17 by Heidi
    Una
    October 18 2018
    It's an endless problem on this diet!I.

    Will have a look, thanks.

    For those suffering from constipation, google ‘linseed ‘ or ‘flaxseed’ bread. This is low carb/keto and works like a charm - just remember to drink sufficient water to help it move along.

  19. 19
    Maggie moore
    October 18 2018
    Keto is impressive and results based.
    Citing a study of THREE persons to make a case for it is NOT.
  20. 20
    Monica Hocking
    October 18 2018
    I was diagnosed with diabetes 7 months ago at 11.5. Six months on it is 5.5. All due to lchf and intermittent fasting.
  21. 21
    Penny
    October 18 2018
    Since going low carb i no longer have to take metformin and all my.blood results came back normal, weight is also starting to come.off,doctor is very pleased with my results, I am feeling so much better and healthier, still have a way to go but i know i can do it
  22. 22
    Susan Kundert
    October 18 2018
    One of the things that concerns me about the whole fasting concept is the confusion between "time-limited eating" (a.k.a., not snacking, not constantly eating), and multi-day fasts. I have had enormous success (A1c at 4.8, weight at goal and below, clothing size at 0 -2) just going keto with 2 meals a day, and NO SNACKING. This is probably 16/8, in fasting lingo. But on the official Fung FB page, there is mass confusion. People who really don't observe the fundamentals of ketogenic eating are obsessing about doing week-long fasts, and refeeding with garbage. My belief is that this is completely misguided. This is not rocket science. A basic ketogenic diet, with time-limited eating, will be more than enough to get most of us where we need to be. I am concerned that the emphasis on ever-longer periods of not eating has become a fetish for disordered behavior. It is normal to eat! It is not normal to repeatedly refrain from eating for a week or more at a time. Fasting as an end in itself threatens to become a substitute for living a productive life.
  23. 23
    Mary Ross
    October 18 2018
    I have been eating low carb, 50+ gm daily, for several years. When I began, constipation was a problem, along with leg cramps. My functional medicine doctor advised increasing my daily magnesium supplement and both problems ended.
  24. 24
    Vern
    October 18 2018
    I dropped my Insulin, and four other diabetes related medications 4 days after starting LCHF in February of 2017 and with the help of the occasional fast up to five days have maintained an HbA1c of less than 6.3 and hope to been under 6 next blood test. I was never under 7 with the insulin and meds and getting worse over 23 years. I am now promoting this life changing ancient diet to everyone who will listen.
  25. 25
    Reply to comment #5 by Jared
    Peter
    October 18 2018
    “I'm interested in the language of "Reversed" vs. "well controlled." To me, reversed would mean that if you gave these subjects a glucose tolerance test, they'd have non-diabetic blood glucose levels at the end of the test. Is that what is happening?”

    What you are referring to would mean cured. Reverse implies that the glucose levels have reverted back to within “normal” levels. Regardless, reversing diabetes stills allow someone with type 2 to reap all the benefits of being ‘cured’ similar to a cancer patient who has gone into remission. Yes, I am shouting from the mountain tops, because unlike my grandmother and all who have suffered needlessly not knowing that there was another way! I feel privileged and fortunate to live in the times that we do. Education is power!

  26. 26
    Reply to comment #10 by Michael
    Una
    October 18 2018

    I have found that constipation in KETO is often a result of your macros not being in sync. Make sure you keep your fat intake up. 75% fat, 20 % protein, 5% carb. My fitness pal app is a good macro calculator to use.

    What are macros? I though we only had to cunt carbs?

  27. 27
    Rondal
    October 19 2018
    I started keto in June with 16:8 IF,A1C went from 9.2 to 7.0 and lost 30 pounds. Doctor is extremely happy. Stopped taking all sugar medicine when I started keto. It took 4 months to get my blood sugar levels to normal levels on a daily basis. I also have the dawn effect but it is starting to go away.
  28. 28
    Bob Harris
    October 20 2018
    I'm done asking for permission after 15 years of doing it their way only to be told that the oral medications not working and I'm going to have to start on insulin I'm insulin resistant it is idiotic to think that giving me insulin in my insulin resistant state is going to improve me or help me in anyway I've started to take matters into my own hands safely testing slowly it's working for me if he can't abide by my choices then I'll fire him and get another doctor
    Reply: #29
  29. 29
    Reply to comment #28 by Bob Harris
    Gentiann
    October 20 2018
    Good for you, Bob!
    Sometimes, it's better to have a "don't ask, don't tell" attitude. However, don't fire your doctor yet: surprise him in 6 months with your next blood test and weight loss. This may not make him a convert but, at least, bring him to raise some questions.
  30. 30
    Reply to comment #4 by Peter
    Dan
    February 24 2020
    I’ve been I.F here and there for about a month and a half, I’m down 22 lbs, my blood glucose is 117 right now and that is fasted, it’s getting better and better. I feel great. Do I need to worry about hypoglycemia? I take metformin, lisinipril and atoravastin. My a1c had gotten to 9.3 before all this, my doctor told me I need more meds and I don’t want more, so I’m avoiding her so she can see I.F works I do I.F, low carb and workout. I’m going to get off all this crap
  31. 31
    John Taylor
    April 17 2020
    What would be great to learn is what is the optimal fasting period for seeing results in lowered blood glucose levels and A1C. For example, I am entering the 3rd day of a weekly fast. Is it worth the effort of a 3 day fast or can I get similar results with shorter and maybe more frequent fasting periods?
    Reply: #32
  32. 32
    Reply to comment #31 by John Taylor
    Crystal Pullen Team Diet Doctor
    April 17 2020

    What would be great to learn is what is the optimal fasting period for seeing results in lowered blood glucose levels and A1C. For example, I am entering the 3rd day of a weekly fast. Is it worth the effort of a 3 day fast or can I get similar results with shorter and maybe more frequent fasting periods?

    John, you may find this video helpful https://www.dietdoctor.com/understanding-and-treating-type-2-diabetes...

  33. 33
    brookeaburbach
    August 3 2020
    We have to take our health into our own hands. Most doctors just don't get it. Sad but true...
  34. 34
    Janice Kremer
    January 7 2021
    Aside from the hunger, I have legs that feel creepy when my blood sugar drops below 100. Most am blood sugars are in the high normal. When I was diagnosed with type 2 diabetes, my a1c was 13.0 and prescribed 5 units of insulin daily. Which I put in the refrigerator (it's still in there). I dropped my calories to 1000/day and started walking 4 to 8 miles/day. With in 6 weeks my a1c dropped to 8.3, since then it has been below 6 and I lost 65 pounds. Lately I've been gaining weight without changes in routine...what to do??
    Reply: #35
  35. 35
    Reply to comment #34 by Janice Kremer
    Kristin Parker Team Diet Doctor
    January 7 2021

    Aside from the hunger, I have legs that feel creepy when my blood sugar drops below 100. Most am blood sugars are in the high normal. When I was diagnosed with type 2 diabetes, my a1c was 13.0 and prescribed 5 units of insulin daily. Which I put in the refrigerator (it's still in there). I dropped my calories to 1000/day and started walking 4 to 8 miles/day. With in 6 weeks my a1c dropped to 8.3, since then it has been below 6 and I lost 65 pounds. Lately I've been gaining weight without changes in routine...what to do??

    It can be tough to say, but here is our top guide to weight loss that may be helpful.
    https://www.dietdoctor.com/how-to-lose-weight

  36. 36
    Reply to comment #12 by Mark
    George Rodriguez
    February 22 2022
    my previous doctor told me the same thing so i listened, and just went on a bad binge for over a year. My A1C was around 13-14 last year, and has gone down slowly. Had a serious upper respiratory issue after a Covid bout in October and have been working out and eating healthy since. my last A1C in December was 9.1 and I'll be seeing my current doctor in March. Hoping my number is around 5.5 to 6.5 so I can get off insulin pen....started fasting yesterday and am going to 'will' my body to produce positive effects because the mind is stronger than the body!

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