Intermittent Fasting with Chronic Disease

“Can I really try intermittent fasting with my chronic disease – diabetes, atrial fibrillation, kidney disease, medications…?”

As a Family Physician, I am asked that question regularly. It’s an ironic questions really. Fasting to lower insulin levels should be the correct remedy for diabetic patients. Controlling diabetes should help kidney function. All of that should decrease the need for medication. Circling us right back around to fasting being a good thing.

Can You Intermittent Fast with Chronic Disease?

You would think the thought process would be more along the lines of, “Why wouldn’t you try intermittent fasting?”

Instead, patients are terrified of it. They feel it is dangerous and completely off limits. And I know why. They have been told “Consult your Doctor” so many times that they are terrified of changing things up without approval.

A little fear can be a good thing in many ways. Medications need to be monitored by your Doctor and will likely need to be decreased (yeah!) with weight loss. Exactly our goal.

Fear to the point of inaction is NOT a good thing. And fasting, with most chronic diseases is fine. You just need closer monitoring and a few considerations while fasting.

So, let’s discuss intermittent fasting with some of the most questioned chronic diseases …

Intermittent Fasting with Diabetes

Can you fast with Diabetes? Yes, you can BUT you do need to “Consult Your Doctor” before you start. Decreasing blood sugar levels is a main goal of intermittent fasting making it ideal for diabetics.

The issue with fasting in diabetics involves your blood sugar levels dropping too low with fasting. That is especially true for patients that are on insulin treatment or sulfonylurea medications (glyburide, glipizide, etc). Your medications will need to be adjusted around your fasting schedule. Your Doctor can help you with that plan.

You will likely want to start with the time-restricted eating pattern of fasting rather than the longer fasts. And remember that Metformin needs to be taken with food so you will want at least one standard meal-time per day.

Don’t forget to continue to check your blood sugars 3-4 times a day even though you are fasting. It will prevent you from dropping too low and with your medication dosing for future fasts. If your sugars do start to dip, you will want to break your fast and have a snack. And then adjust your medication dose accordingly with your next fast.

Dr. Jason Fung, author of The Obesity Code, wrote a book specifically for diabetics on fasting called The Diabetes Code. In it, he recommends allowing your blood sugars to run a little higher than normal on fasting days in order to prevent low-blood sugars. He maintains his obese diabetic patients on a 36 hour fasting schedule 3 times a week.

intermittent fasting with chronic disease

Intermittent Fasting with Atrial Fibrillation

Can you fast with atrial fibrillation? This is the big MAYBE of the group. Studies have shown atrial fibrillation can be triggered by ketogenic diet. And many cardiologists would argue against the ketogenic diet for patients with atrial fibrillation.

Intermittent fasting with a low-carbohydrate diet can, but does not always, put you into ketosis (more on that to come!). I placed this on a medical forum and started quite a cardiology debate. Some argued that these studies were small in size and the carbohydrate limitations varied. Others argued that low-carb/intermittent fasting is not safe for patients with atrial fibrillation based off those same studies.

This issue was discussed at the recent Mayo Clinic 19th Annual Conference on Nutrition and Wellness. The conclusion to the in depth review was similar to that of so many diets – we need further studies to confirm.

I would recommend talking to your cardiologist if you struggle with atrial fibrillation and would like to try intermittent fasting. The low-carbohydrate aspect is equally important – perhaps considering Mediterranean diet instead of low-carbohydrate would be helpful. In most studies, the low-carbohydrate aspect is what was studied not the fasting.

Intermittent Fasting with Electrolyte Issues

If you have a history of low sodium or low magnesium levels then you will want to be careful with fluid replacement while fasting. Make sure that you are taking a magnesium supplement and drinking broth with your fasts. Low magnesium levels may also play a part in the atrial fibrillation response to low-carbohydrate intermittent fasting diet.

Intermittent Fasting with Kidney Disease

Can you fast with kidney disease? Yes. Just make sure to consume fluids. Our kidneys like to be wet so drying them out is the biggest concern with intermittent fasting.

Intermittent Fasting with Your Medications

Can you fast if you take medications that require food? Yes, you can. Make sure to set a fasting schedule that fits your medication dosing, though. If you choose the 24 hour fast, you will have dinner every night. Medications dosed once a day will work with that schedule.

If your medications are dosed more frequently, require food, and you would like to consider fasting, talk to your Doctor. Many medications have an extended-release form that can be dosed daily. That alone may solve your problem.

Simple Solution: Intermittent fasting for weight loss can be done with nearly all chronic medical diseases (except atrial fibrillation potentially). Make sure to talk to your Doctor about your medications, monitor your blood sugars, and drink lots of fluids while fasting.

For more on The Diabetes Code, check out:

Want to read the studies on atrial fibrillation and ketogenic diet yourself? Check out: http://Low-carbohydrate diets and risk of incident atrial fibrillation: a prospective cohort study (J Am Heart Assoc 2019;8e011955)

For more blog posts on Intermittent Fasting and Diet, check out: