BCAA — what the science says

In a nutshell

Muscle protein synthesis is driven by essential amino acids — which is why experts recommend whole proteins that contain all nine.¹
According to a review of human studies, the claim that BCAAs alone build muscle is not supported.²
BCAAs ease post-workout muscle soreness only a little and briefly.^3,4

1What BCAAs are

BCAAs are three essential amino acids: leucine, isoleucine and valine.² All nine essential amino acids are in EAA products.

Expert recommendation 1.4–2.0 g/kg The International Society of Sports Nutrition (ISSN): for building muscle, 1.4–2.0 g of protein per kilo of body weight a day is enough for most athletes, in doses of 20–40 g. Muscle protein synthesis is driven by essential amino acids, so whole-food proteins that contain all of them are preferred.¹

2Do they build muscle?

Moderate evidence — a review A review of human studies: the claim that BCAAs alone stimulate muscle protein synthesis is unwarranted. The body has to take the other essential amino acids from breaking down its own muscle.²

Weak evidence — a small study +22% In a small study of 10 trained men, 5.6 g of BCAAs after training raised muscle protein synthesis by 22% compared with placebo.⁵

3Recovery

Moderate evidence 24 h A summary of randomised trials in trained men: BCAAs lowered a marker of muscle damage (creatine kinase) up to 48 hours after training, but muscle soreness only during the first 24 hours.³

Weak evidence 8 studies Another summary of 8 small studies with 61 people found less muscle soreness after exercise with BCAAs.⁴

What to take from this

Eating enough protein? You don't need extra BCAAs — food with whole protein or whey protein is better.^1,2
For post-workout soreness, expect at most a small, short effect from BCAAs.³
ForkRep shows your protein for each day and your target based on body weight.

Sources

Written on 9 Oct 2026, based on studies available at that date. Newer research may change the conclusions.

Jäger R. et al. (2017). International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr 14:20. doi.org/10.1186/s12970-017-0177-8
Wolfe R. R. (2017). Branched-chain amino acids and muscle protein synthesis in humans: myth or reality? J Int Soc Sports Nutr 14:30. doi.org/10.1186/s12970-017-0184-9
Khemtong C. et al. (2021). Does branched-chain amino acids (BCAAs) supplementation attenuate muscle damage markers and soreness after resistance exercise in trained males? A meta-analysis of randomized controlled trials. Nutrients 13:1880. doi.org/10.3390/nu13061880
Fedewa M. V. et al. (2019). Effect of branched-chain amino acid supplementation on muscle soreness following exercise: a meta-analysis. Int J Vitam Nutr Res 89:348–356. doi.org/10.1024/0300-9831/a000543
Jackman S. R. et al. (2017). Branched-chain amino acid ingestion stimulates muscle myofibrillar protein synthesis following resistance exercise in humans. Front Physiol 8:390. doi.org/10.3389/fphys.2017.00390

This is general information and does not replace a doctor. Food supplements are not medicines; buy them from trusted sellers and talk to a doctor if you are ill or take medicines.