Peptide library / Bones & muscles / Follistatin 344
Follistatin 344
A natural protein that blocks myostatin, a brake on muscle growth, studied mostly through gene therapy.
Effects studied or claimed
What it is used or promoted for, and where each effect has actually been seen
- Muscle mass in muscle disease, studiedSmall human studies
- Muscle growth, promotedAnimals
How it is thought to work
Follistatin binds myostatin and activin, proteins that limit muscle size, so removing them allows more muscle growth in animals.
What the evidence shows
Gene therapy trials delivering follistatin in Becker muscular dystrophy and inclusion body myositis showed early signs of benefit in small groups. Injected protein products are unproven.
Safety and unknowns
Activin and myostatin have roles in the reproductive system and other organs, so long-term safety is unclear.
Regulatory status
Not approved. Sold as a research chemical.
Regulatory status changes quickly. This entry was last reviewed on 27 October 2026. Confirm current status with the FDA before relying on it.
More in Bones & muscles
IGF-1 DES
Wellness and performanceA shortened form of IGF-1 used in labs, sold for local muscle growth.
IGF-1 LR3
Wellness and performanceA modified IGF-1 with an 83 amino acid sequence used mainly in cell culture, sold for muscle growth.
Elcatonin
FDA-approvedAn eel-derived calcitonin analog approved in Japan for osteoporosis pain.
General information, not medical advice. Do not buy or inject unregulated peptides.