Do BCAAs do anything?

Q: Do BCAAs do anything?

Not if you eat enough protein: they raise muscle protein synthesis far less than whole protein, because they are missing the other amino acids.

Not if you eat enough protein: they raise muscle protein synthesis far less than whole protein, because they are missing the other amino acids.

Evidence Moderate Reviewed 3 Oct 2026 Sources 2

Muscle is built from twenty amino acids. BCAAs supply three of them, so they start the process and then run out of bricks. That is why a drink of whey, milk or any meal with protein beats a BCAA drink at the same dose.

The one case where they are not useless is when food is far away and protein for the day is low, which for most people is a problem better solved with food. If your intake is where it should be, BCAAs are flavoured water.

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Sources 2

Jackman, S.R. et al. (2017). Branched-chain amino acid ingestion stimulates muscle myofibrillar protein synthesis following resistance exercise in humans. Front Physiol 8. 5.6 g of BCAAs after training raised muscle protein synthesis by 22% over placebo, around half of what a similar dose of whole protein produces.
Kaspy, M.S. et al. (2024). The effects of branched-chain amino acids on muscle protein synthesis, muscle protein breakdown and associated molecular signalling responses in humans: an update. Nutr Res Rev 37(2). Review: BCAAs switch on the signalling, but building muscle needs all the essential amino acids present.