Analysis Version
v1
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assertion
Analysis v1
Strong Support

Leucine is a special amino acid that turns on the body's muscle-building machine.

66
Pro
0
Against

Evidence from Studies

Supporting (3)

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Community contributions welcome

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Whey protein but not collagen peptides stimulate acute and longer-term muscle protein synthesis with and without resistance exercise in healthy older women: a randomized controlled trial.

Randomized Controlled Trial
Human
2020 Mar 1

Whey protein, which has lots of leucine, made muscles grow better than collagen protein, which has little leucine — suggesting leucine is key to starting muscle growth.

Untitled Study

Giving leucine to premature baby pigs turned on a specific molecular chain reaction (Sestrin2 → GATOR2 → Rag → mTORC1) that made their muscles grow more protein.

Untitled Study

Leucine was given to baby pigs, and it turned on a cellular switch (mTORC1) that made their muscles build more protein, proving leucine helps muscles grow through this pathway.

Contradicting (2)

0

Community contributions welcome

Untitled Study

Scientists turned on a different switch (c-Myc) and muscles grew protein — even when mTORC1 was completely off. So mTORC1 isn’t the only way.

Untitled Study

Even when chickens got way more leucine than needed, their muscles didn’t make more protein — so leucine doesn’t always work like we thought.

Similar Assertions

Taking leucine — a protein building block — might turn on muscle-building signals in your muscles, but if you're already training and eating enough protein, it won't actually make you stronger, bigger, or recover faster.

20
0
85%

Even though leucine (a protein building block) turns on muscle-growth signals in the body, if you're already eating enough protein, taking extra leucine won't make you stronger, bigger, or recover faster.

20
0
85%

Taking leucine supplements won’t help young athletes build more muscle, get stronger, or recover faster—even though leucine is known to trigger a muscle-growth signal in the body.

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80%

Taking extra leucine pills won’t help you build more muscle, get stronger, or recover faster from weight training if you’re already eating enough protein.

20
0
76%

When you lift weights, your muscles turn on a specific molecular switch called mTORC1, which helps build more muscle protein. But just because this switch flips on right after a workout doesn’t mean you’ll definitely get bigger muscles over time—it doesn’t always line up.

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