Fasting to control BG

Wasn’t sure if this should go under food or treatment, but since fasting is a lack of food, I picked here. I spent the summer months under the care of a doctor who promotes a LCHF diet with a lot of restrictions, and intensive fasting. Like 7 days or more of not eating food. It was medically supervised. I read the books, the websites, I saw the lectures. It seemed plausible, so I thought “why not?” I wanted to give it a try. As it turns out, intensive fasting is not for everyone. Unlike everyone else I encountered in the program, I adhered to the instructions and my bg and other labs got WORSE. Everyone else was cheating, not adhering and their bg was better, their labs overall were better. I still feel like it is my fault things did not work. By trusting that doctor and participating in their program, I have dug myself into a hole and am now clawing my way out. It is not fun. I just wanted to post this so that others know that if they try intensive fasting and fail like I did, they are not alone.

1 Like

It sounds like an interesting program. Where you doing it solely to control your blood sugar, or was there also a weight loss aspect to the fasting?

I just finished reading the book Good Calories, Bad Calories, which was an amazing read about the science of diet, blood sugar, and weigh control. It made me a firm believer in low carb diets, especially as a way to control blood sugar and weight. The author talks a lot about fasting diets (or calorie restricted diets) in the book and how most of the science actually doesn’t support it as an effective treatment for weight management, and how they may actually be more harmful to our overall health. I would highly recommend it if you haven’t already read it.


They said I could get off all diabetes meds living this way. Didn’t care about weight loss, but wanted to see if I could get off insulin. Supposed to fast for several days at a time in the beginning, then scale back to intermittent fasting, not intensive fasting, and find a schedule that works for the individual. I didn’t mind not eating. But my bg flatlined every time I did a long fast, and never came down no matter how long I did not eat. The more often I did longer fasts, the worse my numbers were, the worse I felt, the worse my labs were. And the doctor’s office was not much help.

Love Gary Taubes! he has another book coming out soon. :slight_smile:

If you don’t mind the question, are you diagnosed with T1 or T2 diabetes?

As a T1D, I could never stop insulin even if I didn’t eat for extended periods. I suspect that my results would align with yours on that program.

I have used intermittent fasting for 24 hour periods and it had a good effect on my blood sugar levels. I still run my basal insulin during any fast. It makes me a little more insulin sensitive.

Remember, though, that in the absence of ingested glucose, our livers slowly secrete glucose into our bloodstream in the form of glycogen, which is what basal insulin like Lantus or Tresiba helps to control. So maybe your liver is producing a little too much glycogen. I suggest drinking more alcohol to teach your liver a lesson. I recommend tequila.

Terry4, I had several changing diagnoses and the latest is type 2. I use intermittent fasting and lchf but the intensive fasting is what really got me into trouble.

Edit: Turns out I am not type 2. Found out a little while after fasting failed for me.

David48, I was told longer fasts would deplete the liver of its stores, then I would expect to see my bg drop. I’m thinking of avoiding alcohol for a little while. My liver enzymes are still up a little bit. :frowning: But I like your idea! :slight_smile:

1 Like

Jason Fung has been advocate low carb diets and intermittent fasting as a cure to diabetes and that it also prevents diabetes. I actually think low carb diets can really help with managing diabetes and intermittent fast can be good. When I challenged him on his use of the terms prevention and curing diabetes he lashed out at me, apparently not understanding that you actually can’t prevent or cure diabetes. And then when I pointed out that low carb and fasting didn’t fix my diabetes he had the nerve to tell me “You just aren’t doing it right.”

Extended fasting is actually not good for you. Certainly not a week. It can mess up your metabolism fooling your body into thinking that you starving to death. And the plain fact is the your diabetes may not be controllable with diet and exercise alone, you may just need a basal insulin to get you fasting blood sugars under control. Insulin was the only thing that helped me. It is far better to use insulin and have a normal fasting blood sugar then spend years pursuing treatments that just won’t work and leave you feeling blame for not “doing it right.”


Hi Brian

Sent you a private message. I am familiar with that doctor and his paradigm.

To be clear, glycogen complexes are the massive glucose chains that the liver (and large muscle) use to store glucose. It isn’t ever released directly into the bloodstream – glycogen complexes are HUGE, containing tens of thousands of individual glucose molecules.

During fasting metabolism (any time approximately 2-3 hours after finishing eating) the liver maintains BG levels through glycogenolysis, breaking glycogen complexes down into glucose and releasing THAT into the blood.

Someone behaving like a high priest zealot, rather than rationally scientific.

I don’t know if he actually has anything real to contribute on this topic, but that sort of behavior puts them instantly in the “no credibility” bin for me. Someone I won’t listen to.


Great explanation. Thanks.

The question I would ask myself is this: Is this anyway to live?

As much as I’d like to be free of insulin, I need to eat and I need carbs in my diet. My body’s problem is that it doesn’t produce enough insulin. There is no diet in the world that will give me the ability to nourish the cells of my body without insulin.

Anyone who tells me otherwise is either dishonest or very uninformed.

Every once in a while (when I’m in a bad mood), I’ll interject myself into discussions from kale shake kooks and tell them that they’re all wet. They don’t like it, naturally, and often accuse ME of not knowing what I’m talking about.

“You’re just regurgitating Web MD.”

No. I am the person responsible for the 24/7 365 treatment of a chronic disease that is often as frustrating as trying to herd cats.

It sounds like you know enough to call “baloney” yourself, though.


I have read that the initial treatments for diabetes before there was insulin was fasting until blood sugars normalized, followed by introduction of low carb foods to tolerance… sometimes simply a diet of fats, a little protein, and a little green vegetables. Of course, some people had no tolerance and due to lack of insulin to drive energy into their cells eventually starved to death.

If one is insulin deficient, no matter how long one fasts blood sugars may not come down to normal.

I personally have found that intermittent fasting is an excellent tool to reduce insulin demand and help stabilize blood sugars, but that doesn’t take away the need for basal insulin… No matter how long I don’t eat for my blood sugar will still be higher than normal without insulin…

1 Like

I will say that many, many people have great success with low carb diets. They have great blood sugar control and seem to be very happy with their food choices.
I am one of those people who love a big juicy hamburger on the big bun with the works on it along with fries and Cole slaw. Yeah, I love my carbs. Yes if I keep them lower blood sugars are a little better but my diabetes is harder enough without eating what I want to eat.
Last month I was in major basal testing mode and was going for long periods of time without much carbs at all. It was brutal. And was spilling ketones. Finally one of the endo’s I am working with said, eat some carbs for goodness sakes!
And I happily went back to my carbs 20-50 per meal and ketones went away and I was so much happier.
Low carb is not for everyone and fasting can be a very bad thing if it goes for too long. But everything in moderation is a good thing. And as always YDMV! Just like mine does everyday!

Thanks for posting this, your right at times we think why is this not working for me and it is others. I have done things like this also not so much fasting but other things docs wanted.


I am finally trying an extended fast. Why you might ask?

  1. I have read the works of Jason Fung, and i think that they have value - particularly in type 2 management (no one can fast out of type 1). In terms of diabetes management, though, I am more a Berstein Lady.

  2. From my readings on ketogenic diet and ketosis, it would appear that ketosis is at least partially protective in minimizing muscle loss that may be feared in extended fasting… and fasting is quite distinct from the metabolic effects of very low calorie intake… particularly if that low calorie intake includes enough carbs to preclude ketosis.

  3. I have lost my pregnancy in the past week at 9 weeks … and I feel fasting is a cleansing spiritual thing to do. I feel that this is the right time to try fasting.

  4. I am moderator of a ketogenic group in Philippines, along with a group of very geeky friends. We hare having phenomenal results with reversing type 2 diabetes (in some cases), and at least dramatic improvements in others. Major weight loss in morbidly obese people. We do recommend Intermittent Fasting to those who want to try it (particularly, we take the eat when hungry approach). Some of our members (and my very geeky friends, which includes a medical doctor) are very interested in extended fasting, and have been trying it. So I also thought I should try it. [hahaha… peer pressure… yes, that did play a role in motivating me to ‘try’ this].

  5. There is a theory that fasting helps the body reset and renew. Because, as part of self preservation, the body will first cull and use all the cells that are least healthy. Autophagy. Can’t hurt, particularly now when my hormones are kind of limbo and my body will take a few weeks to get back on track.

  6. I am considering a possible career change, to nutrition and lifestyle coaching in the next few years (looking at possible courses now), and although the establishment doesn’t support such things, I want to have personal experience with doing this.

  7. I do want to lose weight.

  8. Just because.

  9. My fasting approach includes free intake of water, coffee, both black and with a little cream, a little calamansi juice with water, chicken or other soup broths, a shot of jin or vodka is allowed (I put it in my calamansi juice and water - most pleasant). I am also taking a multi mineral supplement, and additional salt.

  10. I am measuring blood sugars using Freestyle libre, blood pressure, and weight daily. I just measured breath ketones today.

Today is day 4 of my extended fast, and I intend to fast for another 1 - 3 days, depending on how I feel. (it is now Wednesday afternoon and I last ate on Saturday evening). I am finding this a pretty amazing experience, so far.

Saturday night I took my usual insulin dose. Sunday morning I woke up high (that is also because I had eaten out the night before, and not my accustomed foods). I cut my insulin dose by 50% starting on Sunday for basal. And bolus only for corrections. Note: i am probably LADA, and should have some residual insulin production. So here are my results so far:

Sunday: Fasting BS = 112, BP 128/80, total insulin dose = 17 Units, weight 88 kg (about 2 kg higher than usual - maybe water retention from Saturday night food and drinks).
Monday: Fasting BS = 86.5, BP 118/77, total insulin dose = 13 U, weight = 86.5 kg
Tuesday: Fasting BS = 72, BP 110/78, total insulin dose = 7 U, weight 85.8 kg. Tuesday night I used 5g of sugar to raise blood sugar slightly before bed (I was getting nervous about low sugars, and still having possible insulin on board).
Wednesday: Fasting BS = 68, BP 108/70, total insulin dose = 1U, weight = 83.8 kg
(I still had to counter the Dawn Phenomenon as my blood sugars went from 68 to 110 in 30 minutes after getting up) - but since then after the correction hit, my blood sugar is sitting nearly flat at 3.3 - 4.0 (60 - 72). I tested breath ketones this morning and they were pretty low at 4.4 ppm. But still ketosis.

For those worried about me, I am checking in with my crazy doctor friend daily (maybe we should both be worried about) and the fast will be stopped if there are any concerns. The interesting things are: -

  1. Amazingly I am not hungry. I did not expect that I would not feel hungry… I have cooked meals for my children, and gone grocery shopping, including walking through food courts, with no problems.
  2. I am feeling pretty clear and calm mentally. Yesterday, I actually completed all the items on my to-do list, which is very unusual… today I’m not so busy… hence playing online. I am working normally and doing all my normal activities (except eating). This included a light treadmill session this morning, that felt great!
  3. It is so freeing not to be thinking about food all the time.
  4. Fasting does not kill a person, and may not even cause suffering - this is a pretty major realization (of course it has to be short-term as one does not want to actually starve).

I fully know and expect I will be back on insulin once I start eating again…

After this is done, and after a break of normal low carb/ keto eating, I intend to personally experiment with a few weeks of protein sparing diet (this is low fat, low carb, and moderate protein), and in a few months, I will likely consider doing it again…

I will update this post once I finish a few more days… and the aftermath impact on blood sugar and weight once I start eating again (I have a baptism to attend on Sunday, so I should ease back into food with a light meal on Saturday night).