‘Is it okay to have cheat days?’

Ask Dr. Jason Fung

Can you do intermittent fasting if you have gout? What does it take to break a fast? And is there any risk of developing vitamin deficiencies with intermittent fasting?

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

Cheating or off-days

I know, I know, I know… beer is bad, bad, bad for keto. However, I am a homebrewing hobbyist, and a member of a homebrewing club.

I’m committed to going keto but, without going overboard, would like to maybe have one day a week or every two weeks where I have a couple of craft beers.

What are your thoughts on cheat days?


It all comes down to your goals. Obviously, if you have a cheat day one day a week, and you are reaching your goal of weight loss, or diabetes reversal then keep doing it. If, however, you have plateaued or are not reaching your goal, then the cheat days may need to be restricted. The results will vary person to person, so you need to judge for yourself how well things work.

Diet Doctor has a full guide on cheating which may provide more information.

Dr. Jason Fung

Uric acid and intermittent fasting

Hello, can you please explain to me why you should not do intermittent fasting if you have gout?


Intermittent fasting can increase uric acid levels which can theoretically lead to gout. I say theoretically, because no study has ever shown that, and the current evidence (which is very sparse) is that fasting increases uric acid, but not gout. Gout is caused by the precipitation of uric acid crystals in the joint space. Why uric acid increases is likely due to renal reabsorption of uric acid, so making sure that you get enough hydration and salt may be important to reducing the likelihood of gout.

You can read more in Diet Doctor’s complete guide on gout.

Dr. Jason Fung

Heavy cream vs breaking an IF

Dr. Fung, first thank you so much for your help and the information you have shared. Will two table spoons of heavy cream in my morning coffee break my fast? Thanks in advance.


Technically, yes. The classic fast is water only, so anything else is technically breaking the fast. But that doesn’t mean you can’t get great results using coffee and cream.

Since there are no studies on this, in particular, we have to revert to anecdotal evidence and our best clinical guess.

I usually use cream myself. Fasting for weight loss is all about lowering insulin, and the insulin effect of a little cream is small, so you still derive significant benefits.

Dr. Jason Fung

With one meal a day fasting, is there any risk of developing vitamin deficiencies?

With one meal a day fasting, is there any risk of developing vitamin deficiencies, as reduced food consumption also leads to reduced consumption of the volume/quantity of nutrients. I’m talking medium to long term. I am aware that the body can get a lot of nutrients from its reserves, but my question is about the essential ones that the body cannot synthesise and are not stored in fat. How do we compensate for this?

Thanks for your time!

Answer: Eating one meal a day over the long term has never been studied scientifically. So we don’t know for sure. The main issue is whether or not you can get adequate protein and micronutrients in your one meal.

Diet Doctor has a very good, detailed guide on OMAD that you may find helpful.

Dr. Jason Fung



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Dr. Fung has his own blog at idmprogram.com. He is also active on Twitter.

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Dr. Fung’s books The Obesity Code, The Complete Guide to Fasting and The Diabetes Code are available on Amazon.

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