I see mixed opinions about BCAA drinks while fasting such as the following variety:

  1. BCAA drinks in low amounts do not affect a fast.
  2. Don't use BCAA during fasting
  3. Only use BCAA's around a workout when fasted.

Those who recommend #1 or #3 are suggesting BCAA's don't necessarily break a fast, but is that really true?

  • This depends entirely on what you want to get out of your fast. Why would we recommend step 2 or 3 without knowing why you're fasting in the first place. This question is very broad, and opinion-based.
    – Alec
    May 15, 2018 at 16:53
  • Changed my question - by "what I want to get out of a fast", I basically am asking because I want to stay in a fasted state, and BCAA's kick you out of that state, I want to avoid that. But that is where there are contrary opinions. May 15, 2018 at 17:27
  • 1
    The science (as you note) is sort of mixed, but the common theme that I am seeing is that if it provokes an insulin response you have broken the fast.
    – JohnP
    May 15, 2018 at 17:40
  • Yeah and ultimately I've seen: keep it to 10 grams and your fine... But others say your body will invoke an insulin response for any BCAA. I just read tonight Jim Stoppani says it's fine to take a little BCAA during a fasted workout. It's all so confusing ! May 15, 2018 at 23:57

1 Answer 1


2 - BCAA will definitely brake your fast, as it actually has calories and Leucine (the main bcaa aminoacid) is highly insulinogenic so you will have insuline response to that.

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