Blocking a protein called myostatin causes rodent muscles to grow about 20-30% larger over a few weeks.

See the scientific wording

Blocking myostatin (GDF8) in rodents increases muscle mass by approximately 20-30% within a few weeks.

Supporting

Weak

2 studies

Correlational — new studies may shift this

Mixed evidence

2 low-scoring studies link this claim to the outcome, but causation is not established.

What the research says

2 studies reviewed

Supporting (2)

Weak

p21-Activated Kinase 1 Is Permissive for the Skeletal Muscle Hypertrophy Induced by Myostatin Inhibition
Cross-Sectional StudyAnimal2021
The study gave mice a treatment that blocks myostatin (a protein that limits muscle growth), and the mice's muscles grew 25-30% bigger, which matches the claim that blocking myostatin increases muscle mass by 20-30%.
A VLP-based immunogen that elicits selective anti-Myostatin antibodies, enhances muscle mass and strength, and reduces adiposity
Randomized Controlled TrialAnimal
Scientists gave mice a vaccine that blocks a protein called myostatin, and found their muscles grew about 20-30% bigger, just like the claim says.

Contradicting (0)

None

No contradicting studies found yet

That doesn't mean it's settled — it just means no study has tested the opposite.

Quality-weighted scoring: we follow the GRADE framework — each study is rated High, Moderate, Low, or Very Low based on study design, methodology rigor, and risk of bias. A single high-quality RCT can outweigh several weaker observational studies.

Scores reflect study quality, not just count.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 2 supporting studies

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