Dr. Jason Fung answers questions about intermittent fasting

March 20 2016 by , medical content by in Dr. Jason Fung, Intermittent fasting, Q&A

Do you want to know more about intermittent fasting for weight loss or diabetes reversal? Learn from Dr. Fung’s answers to common questions. He’s a Canadian nephrologist and a world-leading expert on intermittent fasting and LCHF, especially for treating people with type 2 diabetes.

Here are a number of questions answered by Jason:

High morning blood sugar

Dr. Fung,
I have read and re-read everything on your blog and this site for nearly a year. I have T2D and have been following LCHF, and doing some IF. I currently take 1000 mg of metformin. This was recently reduced because my A1C came down to 5.2! I feel great about the progress I have made but the dawn phenomenon still has me puzzles. My numbers in the morning are always in the 130’s. I want them lower!

Should I not be concerned about this? I have read your blog about DP, but I’m not quite sure if you are saying that high numbers in the morning don’t matter or if I should expect to see them come down in time. It seems to me that recently my morning numbers have gone up- Can you clear this up for me?

Dr. Jason Fung: Your DP indicates that you have not entirely gotten rid of insulin resistance. Sometimes it just takes more time. Insulin resistance is a time dependent phenomenon. It can take years to develop and can take months-years to go away.

I wouldn’t worry particularly about it. But it does mean you have more work to do.

Read more in Diet Doctor’s guide to insulin resistance.

Is drinking broth really fasting?

Dear Dr.Fung,
Thank you very much for all your help and for the lovely website,
I was just wondering regarding the broth, how come we can have it during the fasting since I believe it contains some fat/ some proteins/ and some calories from the bone and meats which are boiled… I’m just thinking aren’t we are better off without it and stick to water tea, for a proper fast?
Thank you

Dr. Jason Fung: Yes, the broth technically breaks the fast. We use it more in extended fasts for 2 reasons. First, the small amount of protein makes very little difference to most people. Second, it reduces the risk of re-feeding syndrome. If you would like to stick to water fasting, that is fine, too.

Should I eat more often?

Dear Dr. Fung,
This is one of the best life changing regimen I have ever done and it is showing great results in my blood work as well, recently I’ve been going through a body fast were I wake up not hungry and eat only when I feel the need to (still trying to control that, wait too long I guess before eating) as well I workout twice a day.

Do I continue with this concept where I eat when I need to or time it in a way to eat every 8 hrs, it’s very confusing since I am still considered a Diabetic (hopefully not for too long).

Just to add, I was diagnosed as a diabetic in Jan 2015 with A1c of 6.5; Lantus 8 units; 1000mg Metformin and before the diet the A1c was 5.5 on Oct 2015, now after 3 months my A1c is 4 and recently taking 500 mg Metformin and no Lantus (had to reduce/remove since I went into hypo a few times). Sadly I live in Bahrain and there are no Doctors that agree to this diet and no one to support, so doing this on my own with experimentation and checking my results on a monthly basis (family has a history of BP and Diabetes with other health issues like GERD and hypertriglyceridemia which I think this is norm with T2D).

I’m guessing I am doing it right since I have done the research and saw almost all your content on the site with monthly blood works.

Dr. Jason Fung: If you are not hungry, you should not eat. That is your body telling you that it has enough energy. Where is it coming from? Your own fat stores! That’s excellent. So, continue to let your body burn the fat and don’t eat.

Intermittent Fasting for Beginners

More About Intermittent Fasting and Diabetes

How to Maximize Fat Burning – Dr. Jason Fung

How to Fast – The Different Options – Dr. Jason Fung

The 7 Benefits of Fasting – Dr. Jason Fung

The Top 5 Myths of Fasting – Dr. Jason Fung

Breakfast! Is It Really That Important? – Dr. Jason Fung

The Most Common Questions – Dr. Jason Fung

How to Get Started with Fasting – Dr. Jason Fung

The Perfect Treatment for Weight Loss and Diabetes – Dr. Jason Fung

The 2 big lies of type 2 diabetes – Dr. Jason Fung

19 comments

1
Chris Roberts
September 16 2017
Do you have any suggestions for someone who wants to fast but has acid reflux? Can I take apple cider vinegar, baking soda and lemon water to help with it? I do take prevacid, but sometimes it still pops up during the day and finding on this fast day I am feeling the reflux. Thanks
2
Dorothy Krause
October 22 2017
I told my 40yr old daughter, who is obese, that I was on a 3 day fast (I'm at goal 57 kg). I was hoping this would be a gentle way to tell her about fasting. Well she told her Exercise Physiologist who told her " get in touch with your mother tell her, her muscles are being destroyed and particularly her heart muscle". Well it sure did rattle me. I've read the OC and TCGTF as well as many other books, listened to the podcasts, the webinars and have been an active participant on the Support FB page. I have lost a lot of confidence. Am seeing my dr and having bloods done this week. (I do this 6 monthly.) Apart from some palpitations which a dose of salt has fixed I'm 68 and in pretty good shape. Walking regularly for an hour.

I need your reassurance.
3
Gina
June 22 2018
I am currentlyon dialysis I am also a diabetic has kidney failure and have hypothyroidism I would like to know if fasting is safe for me.
4
Helen
August 2 2018
Is it okay to fast when you have benign pvcs? I get alot of them when I don’t eat enough. So scary! But, I really want to fast longer than 16hrs.

Thank you!
5
Paula
October 22 2019
I am T2D. I am in the middle of my first 36 hour fast. I always have higher BG in the morning. I thought the fast would help with that but my BG reading was still up higher than before bed. I have read about the DP. I am just not sure what to do?
6
Shay
January 5
I work 11 hr shifts . I sit most of the whole day. I bring a lunch which I pick at all day . It's a small lunch . I stretch through the day . I have a right side near shoulder blade pain which is caused by muscle flare . I can touch my toes . Im 54 and now im gaining weight it my mid section . I really don't know what to do to loose the weight .

Reply: #7
7
Reply to comment #6 by Shay
Kristin Parker Team Diet Doctor
January 7

I work 11 hr shifts . I sit most of the whole day. I bring a lunch which I pick at all day . It's a small lunch . I stretch through the day . I have a right side near shoulder blade pain which is caused by muscle flare . I can touch my toes . Im 54 and now im gaining weight it my mid section . I really don't know what to do to loose the weight .

You may want to try our free two week challenge!
https://www.dietdoctor.com/low-carb/get-started
8
Denise
January 23
I have heard somewhere that Intermittent Fasting can cause an increase in Cholesterol? I have been watching what I eat (loosely follow fast800), increased good fats, exercise daily (walking 50 mins at decent pace - osteoarthritis in hands and feet), fast between 14 - 20 hours regularly,.. but my recent Cholesterol blood test showed high chol - so much that my doctor has put me on medications.. I am trying to avoid medications.. but I also know the risk of CKD due to both hypertension and high cholesterol.. can you point me in the right direction so I can have another 'robust discussion' with my GP.. (evidence based preferred) Thank you in advance.
9
Bob
February 5
Dr Fung, what do make make of this Yale study that links intermittent fasting with Type II diabetes ? https://news.yale.edu/2020/02/04/studies-suggest-new-path-reversing-t...

Reply: #10
10
Reply to comment #9 by Bob
Gentiann
February 6
I just read this report and did not see a reference to intermittent fasting.
I understood that the fast refered to was the overnight fast when the liver produces glucose to keep blood sugar from falling too low. They found that normally the liver can switch off the production of glucose when not needed but that this switch is not working in diabetic mouses. The team from Yale is trying to come up with a drug to fix this problem.
I have a better idea:
not overloading the liver with sugar by eating a very low carb diet.....!
11
Sheri
February 23
So I know you have a bone broth recipe but I was wondering if you have a reccommended vegetable broth recipe for vegetarians. I've found a couple online but not sure if they are right or not.
12
Paris Singleton
April 12
So now that I am down to eating once a day. It seems now that I am falling into a food coma. Even if its just bacon, eggs and toast. I get so sleepy. What are suggestions to combat this. Luckily I only eat breakfast on Saturday mornings with my husband but during the week its just dinner around 4 pm. I get super tired and lose 2 hours of daytime due to being sleep. I have been fasting since Feb. 4th but this tiredness has just hit in the last week or two.

Reply: #13
13
Reply to comment #12 by Paris Singleton
Kerry Merritt Team Diet Doctor
April 12

So now that I am down to eating once a day. It seems now that I am falling into a food coma. Even if its just bacon, eggs and toast. I get so sleepy. What are suggestions to combat this. Luckily I only eat breakfast on Saturday mornings with my husband but during the week its just dinner around 4 pm. I get super tired and lose 2 hours of daytime due to being sleep. I have been fasting since Feb. 4th but this tiredness has just hit in the last week or two.

If you are experiencing extreme fatigue, OMAD (one meal a day) may not be a good choice for you.
This article should be helpful for you! https://www.dietdoctor.com/intermittent-fasting/omad
14
Diane Steves
April 21
I am afraid I will have a lot of extra skin with weight loss. I am a type 2 Diabetic, have a slow thyroid for which I take medication and other health issues. I have slowly lost about 30 pounds by eating low carb and doing intermittent fasting since September 2019, eating at 11:00 AM and then dinner about 6:30 PM and the next day just eating only once with dinner at about 6:30 PM. I have been doing this every other day regiment most of the time. I walk almost every day for about 45 minutes. I am over 60 and have another 100 pounds or so to lose and after a lifetime of gaining and losing, am concerned about extra skin. I have gained and lost 80 pounds in a year several times and my stretch marks, have stretch marks. What can I do to maximize my chances of reducing the extra skin as I go? I have tried to fast more than 24 hours but find I am extremely hungry and feel sick. My blood sugars are improving and I am on less that half the Diabetes medications I started with. If I do eat a carbohydrate for a special occasion, my blood sugar does not go up nearly as much as it used to so there is a definite change in the way my body is reacting.

Reply: #15
15
Reply to comment #14 by Diane Steves
Kristin Parker Team Diet Doctor
April 21

I am afraid I will have a lot of extra skin with weight loss. I am a type 2 Diabetic, have a slow thyroid for which I take medication and other health issues. I have slowly lost about 30 pounds by eating low carb and doing intermittent fasting since September 2019, eating at 11:00 AM and then dinner about 6:30 PM and the next day just eating only once with dinner at about 6:30 PM. I have been doing this every other day regiment most of the time. I walk almost every day for about 45 minutes. I am over 60 and have another 100 pounds or so to lose and after a lifetime of gaining and losing, am concerned about extra skin. I have gained and lost 80 pounds in a year several times and my stretch marks, have stretch marks. What can I do to maximize my chances of reducing the extra skin as I go? I have tried to fast more than 24 hours but find I am extremely hungry and feel sick. My blood sugars are improving and I am on less that half the Diabetes medications I started with. If I do eat a carbohydrate for a special occasion, my blood sugar does not go up nearly as much as it used to so there is a definite change in the way my body is reacting.

It sounds like you're doing as much as you can! If you're feeling sick, it's definitely not a good idea to try and force a fast, especially if you're on medication. Keeping consistently on plan will help with the weight loss also.
16
Fred Wong
June 1
I lost a lot of weight from 130kg to 76kg and went pure carnivorous and most extended fast and OMAD and then eating every 48 hours and then 72 hours and only once 96 hours and no stretch marks at all...I think or might be wrong that extended fast does help with the skin elasticity....
17
Koo
July 8
I am on 5 day water fasting and on day 3. I woke up to my heart racing. Should I stop or carry on. It's scary to see my heart going crazy as though I am running. Could someone answer me quickly? Thank you.

Reply: #19
18
Gentiann
July 8
You probably need salt : drink some broth or something with electrolites.
It seems prudent to stop fasting if you are not feeling well.
19
Reply to comment #17 by Koo
Kristin Parker Team Diet Doctor
July 8

I am on 5 day water fasting and on day 3. I woke up to my heart racing. Should I stop or carry on. It's scary to see my heart going crazy as though I am running. Could someone answer me quickly? Thank you.

Please check in with your doctor to evaluate your symptoms. Dr Fung does not recommend longer fasts without doctor supervision for issues such as this.