Follistatin 344
FST344 — Myostatin Inhibitor
What is Follistatin 344?
Follistatin 344 is a naturally occurring glycoprotein and the most studied isoform of follistatin. It is a potent antagonist of myostatin (GDF-8) and activin — TGF-beta family members that inhibit muscle growth. By neutralizing myostatin, Follistatin 344 removes the primary endogenous brake on muscle hypertrophy and hyperplasia.
Follistatin binds and neutralizes myostatin with high affinity, preventing it from binding to muscle cell receptors. Myostatin normally inhibits satellite cell activation and muscle protein synthesis — removing this brake allows significantly accelerated muscle growth. Animal models with myostatin knockout or Follistatin overexpression show 2-3x normal muscle mass.
Research Evidence
Dramatic muscle mass increases in myostatin knockout and Follistatin-overexpressing animal models — often 2-3x normal muscle mass. Establishes myostatin as a primary regulator of muscle size limits.
Follistatin gene therapy trials in Becker muscular dystrophy and IBM patients showed meaningful muscle function improvements, supporting the mechanism in humans.
Widespread community use in bodybuilding. No controlled human trials of injectable Follistatin 344. Effects extrapolated from animal and gene therapy data.
Evidence grades: Gold = RCT human data · Silver = consistent animal/human data · Bronze = limited or preliminary
Dosing Protocols
Reconstitution Guide
| Vial Size | BAC Water | Concentration | Target draw |
|---|---|---|---|
| 1 mg | 2 ml | 500 mcg/ml | 100mcg = 20 units |
| 1 mg | 1 ml | 1 mg/ml | 100mcg = 10 units |
Frequently Asked Questions
Does Follistatin 344 actually build muscle?
The myostatin inhibition mechanism is well-established and animal data is dramatic. Human injectable trial data is absent — human evidence comes from gene therapy rather than injection. Community anecdotal reports are positive but controlled human trial confirmation is lacking. The mechanism is sound; whether injectable doses reach sufficient tissue concentrations remains the key question.
Is Follistatin 344 detectable in drug testing?
Yes. Follistatin and myostatin inhibitors are on the WADA prohibited list. It is prohibited in all competitive sports governed by WADA.
References
- [1]Lee SJ, McPherron AC. Regulation of myostatin activity and muscle growth. Proc Natl Acad Sci USA. 2001;98(16):9306-9311.
- [2]Mendell JR, Sahenk Z, Malik V, et al. A phase 1/2a follistatin gene therapy trial for Becker muscular dystrophy. Mol Ther. 2015;23(1):192-201.
This profile was prepared using AI-assisted research synthesis. Citations are provided where applicable — verify with primary sources before clinical application.
Share this article