Video post – what breaks a fast?

This week I decided to do a video post instead of a regular written one. Why? No reason. Just to change things up. After about five years of writing a weekly blog, I thought it would be a nice change of pace. Here it is:

Dr. Jason Fung

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  1. Virginia
    I have been reading about autophagy and like the idea of cleaning out the weak and dead stuff from my body. Makes room for healthy new stuff ❤️ My question is does the little bit of cream or tea or broth stop the autophagy aspect of fasting? You mentioned most of the benefits would still be there. I have looked at a lot of videos and stuff on line and came to the conclusion it has to be water fast for this autophagy to happen. I also read it works best from hour 12 to 48 hours after eating. I am just a little bit confused about it. Would love clarification if possible! And Thank You! I love this site and all the wisdom you and the others pass on :)
    Replies: #2, #3
  2. Kristin Parker Team Diet Doctor
    In an answer on another page, Dr Fung has said that a small amount of cream shouldn't break a fast for most people. Unsweetened tea, coffee and bone broth are generally find while fasting.
  3. Aaron
    Hi Virginia. As I understand autophagy it is regulated by mTOR (and the AMPK molecule). Insulin is also involved in that the genes that carry out autophagy are regulated by insulin. When mTOR is upregulated, then no autophagy. When AMPK is low (indicating high energy in cells), also no autophagy. When insulin is high, no autophagy.

    mTOR is very sensitive to dietary amino acids, so cream in your coffee would not add protein and so have little to no effect. Any energy intake would effect AMPK (fat, protein, or carbs) but I understand AMPK to be a long term process. Over long periods of time if AMPK is low, then autophagy may be halted. Seems like cream in your coffee would have little effect on AMPK.

    Cream in your coffee would not have much effect on insulin either.

    Given that mTOR is sensitive to dietary protein, my own wondering is whether broth would have an effect and should be avoided in favor of fat (cream). I'm just learning all of this myself so maybe someone else has some insight there. And I'm not at all an expert so I welcome comments that would help me learn more!

    Personally, I fast 20 hours most days and 60 - 72 hours about 3 times a month. I have (1) coffee with heavy cream every day, whether I fast or not. It does not at all seem to effect weight loss or how I feel during fasting. Maybe I'd eek out a little more benefit without the heavy cream, but my guess is it's negligible? Anyone have ideas on what benefit(s) I may be missing out on?

  4. Cassieoz
    My understanding is that it depends on the reason for fasting. If it's to drop insulin the a little cream or fat in coffee wont make a significany difference. If your aim is autophagy then the fast is a 'no calorie' fast.
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  6. Karyn
    Understand no sugar in coffee or tea...what about keto-friendly sweetener?
  7. 1 comment removed
  8. Nikaia
    Is this the same for collagen powders?
    Reply: #9
  9. Kristin Parker Team Diet Doctor

    Is this the same for collagen powders?

    As collagen has a lot of protein, yes, it likely does break a fast.

  10. Annika
    So I'm new to this...I'm guessing I can't have diet sodas during fasts? What about actual coffee creamer that doesn't have sugar?
    Reply: #11
  11. Kerry Merritt Team Diet Doctor

    So I'm new to this...I'm guessing I can't have diet sodas during fasts? What about actual coffee creamer that doesn't have sugar?

    We recommend avoiding artificial sweeteners completely, and all sweeteners during a fast. The general consensus is that a small amount of heavy cream is OK if needed during a fast.

  12. teacher
    You can use Stevia as sweetener but only one with 0 kcal!
  13. Kristine
    I have a collagen peptide powder 50 calories for 1 tablespoon with 13 grams of protein. I have been fasting for 43 hours so far I had a tablespoon each day of fast did that take me out of autophagy and break my fast? Thank you

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