Follistatin

Overview

Follistatin is a naturally occurring glycoprotein that binds and neutralizes myostatin and activin — TGF-beta family proteins that normally restrain muscle growth — so blocking them is expected to favor muscle gain. It is not FDA-approved for any indication. The most rigorous human work has used AAV-delivered follistatin gene therapy (AAV1-FS344) in small Phase 1/2a trials for Becker muscular dystrophy and sporadic inclusion body myositis, which reported some six-minute-walk improvements and favorable muscle histology with no serious adverse events, but these were tiny, early-stage studies in disease populations, not evidence for healthy-person muscle building. Injectable 'follistatin-344' peptide products sold online are a different, unproven proposition with essentially no controlled human efficacy data.

Commonly Reported Uses

These are uses commonly discussed or marketed by users and vendors — not a list of proven or approved benefits, and not a recommendation.

• Muscle-wasting disorders such as Becker muscular dystrophy / inclusion body myositis (investigational gene therapy; not FDA-approved)
• Muscle growth and strength in healthy adults (marketed claim; human evidence very limited)
• Body recomposition / fat reduction (marketed claim; human evidence limited)
• Anti-aging and longevity (marketed claim; not an approved use)

What to Track

Data points you and your clinician might monitor. For observation only — not a diagnostic protocol.

• InBody/DEXA — skeletal muscle mass and body-fat % over a defined baseline
• Smart scale — weight and body-fat % trend
• Labs — a clinician-monitored panel; follistatin acts on the myostatin/activin axis rather than IGF-1 directly
• WHOOP — recovery score and HRV trend
• Subjective daily check-ins — strength, training performance, tolerability

Sources & References

1. [1]A Phase 1/2a Follistatin Gene Therapy Trial for Becker Muscular Dystrophy — PMC
2. [2]Follistatin Gene Transfer to Patients With Becker Muscular Dystrophy and Sporadic Inclusion Body Myositis — ClinicalTrials.gov (NCT01519349)
3. [3]List of drugs banned by the World Anti-Doping Agency — Wikipedia