Do BCAAs help build muscle?

The evidence says not on their own. Building muscle requires all nine essential amino acids and BCAAs supply only three, so protein synthesis cannot be sustained with them. A complete protein, like whey, supplies all nine and includes the BCAAs too.

Is it worth taking BCAAs if I already take protein?

No. A scoop of whey already contains about 5-6 g of BCAAs with 2-3 g of leucine. Adding BCAAs on top is paying twice for the same thing, and the second time for the incomplete version.

Do BCAAs get rid of soreness?

A meta-analysis finds a small reduction in delayed-onset muscle soreness. It is the best-supported of all the effects attributed to them, and even so it is modest and does not improve strength or performance recovery.

Are they useful for fasted training?

It is the only scenario where people look for a place for them: supplying some amino acids without fully breaking the fast. Even so they have calories, so a strict fast is broken anyway, and a complete protein would give a better result if the goal is muscle.

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BCAA · Weak evidence

Do BCAAs work or are they a waste of money

The short answer. BCAAs are three amino acids: leucine, isoleucine and valine. Building muscle tissue takes all nine essential ones, so giving only three is like bringing three ingredients to a nine-ingredient recipe. The review that looks at this question concludes that the evidence for them working on their own does not hold up. If you already reach your daily protein, they add nothing, and a complete protein usually costs less per serving.

Reviews find no consistent effect. It is listed because it sells, not because it works. No figure on this page is attributed to a specific product: the effect belongs to the ingredient and every number carries its source next to it.

01 What it does and how much

Each row is a measured effect, with the figure the study gives and the source number. Where the evidence gives no figure, the column says so instead of making up a percentage.

Effects of BCAA with their source
Effect	How much	Detail
Muscle protein synthesis	not sustained alone	Synthesis needs all nine essential amino acids. Supplying three, the process runs into the lack of the other six and the body ends up drawing on its own proteins. It is the central argument of the review, and it is basic physiology, not opinion. [1]
Against a complete protein	worse	The ISSN position stand notes that isolated BCAAs do not beat a complete protein, which also brings all nine essentials. A serving of whey has its BCAAs inside. [2]
Post-exercise soreness	small reduction	It is the only effect with some support in the meta-analysis, and it is modest. It does not improve strength or muscle mass: it just makes it hurt a little less. [3]
Leucine per serving	700 to 3000 mg	It is the threshold sought to trigger synthesis, and a 2:1:1 BCAA at 5 g reaches it. The problem is not leucine: it is the six amino acids that are missing. [2]

02 How to take it

Dose. 5 to 10 g per serving in the studies, although the dose does not fix the underlying problem.
When. Around training, which is how they have been studied.
How long before you notice it. There is no demonstrated cumulative effect to wait for.

Details that change the result

Before buying BCAAs, check how much total protein you take a day. If you are below 1.6 g per kilo, that money goes much further in complete protein.
A scoop of whey already carries about 5-6 g of BCAAs, including 2 to 3 g of leucine, and it brings the other six essentials too.
They are safe: the problem is not safety, it is that they do not do what they are credited with.

03 When it makes sense and when it does not

Worth it if

Practically never for performance or muscle.
The only case left standing: prolonged fasted training without being able to take a complete protein, and even then a complete protein is still the better option.
As a flavoured drink to drink more during the session, knowing you are paying for the flavour.

Not worth it if

If you already reach your daily protein. Then they add absolutely nothing.
As a substitute for a protein shake: they are the incomplete, more expensive version.
Expecting to gain muscle or strength with them.

04 Sources

Every figure above comes from here. They are position stands from scientific societies, meta-analyses and peer-reviewed reviews: if a claim cannot hang from one of these lines, it is not on the page. References are cited in their original form.

Wolfe RR. Branched-chain amino acids and muscle protein synthesis in humans: myth or reality? J Int Soc Sports Nutr. 2017;14:30. doi:10.1186/s12970-017-0184-9
Jager R et al. ISSN position stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. Los BCAA aislados no superan a una proteina completa. doi:10.1186/s12970-017-0177-8
Fedewa MV et al. Effect of branched-chain amino acid supplementation on muscle soreness following exercise: a meta-analysis. Int J Vitam Nutr Res. 2019;89(5-6):348-356. doi:10.1024/0300-9831/a000543

This is not medical advice. It is what some studies say about an ingredient, not a protocol for you. With an illness, medication or pregnancy involved, the decision belongs to a healthcare professional who knows you.

Questions about BCAA

Answered with the data on this page

Do BCAAs help build muscle?: The evidence says not on their own. Building muscle requires all nine essential amino acids and BCAAs supply only three, so protein synthesis cannot be sustained with them. A complete protein, like whey, supplies all nine and includes the BCAAs too.
Is it worth taking BCAAs if I already take protein?: No. A scoop of whey already contains about 5-6 g of BCAAs with 2-3 g of leucine. Adding BCAAs on top is paying twice for the same thing, and the second time for the incomplete version.
Do BCAAs get rid of soreness?: A meta-analysis finds a small reduction in delayed-onset muscle soreness. It is the best-supported of all the effects attributed to them, and even so it is modest and does not improve strength or performance recovery.
Are they useful for fasted training?: It is the only scenario where people look for a place for them: supplying some amino acids without fully breaking the fast. Even so they have calories, so a strict fast is broken anyway, and a complete protein would give a better result if the goal is muscle.

And now, which to buy

Prices, kept apart from the evidence

This page explains what BCAA does and deliberately names no brand. The comparison is the other half: 126 products from 18 stores from €17.49 per kg, sorted by price and by how verifiable their certification is.

See the bcaa comparison

Other guides

What each supplement does, with its sources