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No. 018 · GH & Growth · Muscle Growth

Follistatin 344

FS-344FollistatinFST

C Tier C · Animal data how tiers work →
  • Not FDA approved
  • WADA ✗ S4
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Follistatin 344 (no defined sequence)

No sequence on file. We only draw fingerprints from published sequences — this ring motif is a placeholder, never a guessed sequence.

01

Quick answers

What is Follistatin 344?
A recombinant glycoprotein that binds and inhibits myostatin, the primary negative regulator of muscle growth. A ~344-amino-acid glycoprotein (precursor isoform of follistatin) rather than a short peptide.
How strong is the evidence for Follistatin 344?
Tier C (animal data) on the peptidemeta evidence scale. Evidence for the protein is from animal studies; the only human data are small open-label gene-therapy trials (AAV-delivered follistatin), not the protein itself.
Is Follistatin 344 FDA-approved?
No. Follistatin 344 is not approved by the FDA for any use.
Is Follistatin 344 banned in sport?
Yes. Follistatin 344 is prohibited in sport by the World Anti-Doping Agency under S4 (hormone and metabolic modulators).
How does Follistatin 344 work?
Follistatin 344 is a recombinant activin-binding protein that sequesters myostatin (GDF-8), activin A, and other TGF-beta superfamily ligands, preventing them from signaling through ActRIIB. By neutralizing myostatin, it removes the primary endogenous brake on skeletal muscle growth, allowing increased muscle fiber hypertrophy and satellite cell-mediated repair.
What is known about the safety of Follistatin 344?
Gene therapy trials (AAV-follistatin) showed acceptable safety in muscular dystrophy patients. Recombinant protein form has minimal human safety data.

Last reviewed · editorial policy · markdown

02

Evidence

  1. D In vitro
  2. C Animal
  3. B Human pilot
  4. A RCT
  5. S Approved

TIER C — Evidence comes mostly from animal studies.

Evidence for the protein is from animal studies; the only human data are small open-label gene-therapy trials (AAV-delivered follistatin), not the protein itself.

Tiers rate the strength of published evidence — not effectiveness, safety, or a recommendation.

03

At a glance

Routes studied
Subcutaneous, Intramuscular Routes used in published research
FDA
Not approved
WADA
Prohibited · S4 Hormone and metabolic modulators
04

Overview

A recombinant glycoprotein that binds and inhibits myostatin, the primary negative regulator of muscle growth. Follistatin 344 promotes muscle hypertrophy by removing the myostatin brake.

Research status Gene therapy clinical trials for muscular dystrophy; recombinant form has limited human data

05

Mechanism

Follistatin 344 is a recombinant activin-binding protein that sequesters myostatin (GDF-8), activin A, and other TGF-beta superfamily ligands, preventing them from signaling through ActRIIB. By neutralizing myostatin, it removes the primary endogenous brake on skeletal muscle growth, allowing increased muscle fiber hypertrophy and satellite cell-mediated repair.

06

Effects reported in research

Reported outcomes, not promises. These come mostly from preclinical (cell or animal) research and have not been confirmed in human trials.

  • Myostatin inhibition and muscle growth
  • Increased lean muscle mass
  • Improved strength output
  • Potential bone density enhancement
07

Safety & unknowns

Gene therapy trials (AAV-follistatin) showed acceptable safety in muscular dystrophy patients. Recombinant protein form has minimal human safety data. Theoretical risks include disruption of activin/FSH reproductive signaling and fibrosis in non-muscle tissues. Not FDA-approved.

Unknowns. No randomized controlled trials in humans have been published, so human safety has not been established in controlled studies.

Informational only — not medical advice. peptidemeta publishes no dosing, protocols, or sourcing. Talk to a qualified clinician about any treatment decision.

08

Studies [0]

No studies cited for this entry yet.

10

Status sources

Sources behind the tier, regulatory status, sequence and dates on this page.

11

Cite this entry

$ cite --format=apa

peptidemeta. (2026). Follistatin 344. In peptidemeta: The peptide library, ranked by evidence. Retrieved November 8, 2026, from https://peptidemeta.com/p/follistatin-344/

$ cite --format=bibtex 
@misc{peptidemeta-follistatin-344,
  title = {Follistatin 344},
  author = {{peptidemeta}},
  year = {2026},
  howpublished = {\url{https://peptidemeta.com/p/follistatin-344/}},
  note = {Accessed 2026-11-08}
}

Accessed date reflects when you opened this page. Cite primary studies for scientific claims.

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