FST344
Naturally occurring protein that inhibits myostatin and other TGF-beta family members. Transgenic pigs engineered to overexpress follistatin-344 in muscle showed increased skeletal muscle and reduced body fat; this was not an administered-dose finding.
Regulatory status (as of Sept 2026)
Not FDA-approved, no legitimate pharmaceutical formulation exists. Prohibited in sport under WADA S4. Not on the April 2026 503A Category 2 removal list or the July 2026 PCAC agenda.
See the FDA peptide regulatory tracker · Read our July 27, 2026 dispatch on the FDA PCAC peptide vote2 studies referenced · Last reviewed Oct 1, 2026 · Reviewed by The Peptide Dispatch Editorial Team · How we research & label content
Follistatin 344 is a compound studied only in animals and lab experiments so far. Naturally occurring protein that inhibits myostatin and other TGF-beta family members.
| Half-life | Not established in published research |
|---|---|
| How it's given in studies | Subcutaneous injection |
| Research stage | Preclinical (animal) |
| Dosing | Published research: No exogenous dosing study exists detailsNo exogenous dosing study exists. The muscle-mass evidence comes from transgenic overexpression of human follistatin-344 in Duroc pigs and from myostatin-pathway genetics, not from administering a measured dose of peptide.Community-reportedCommunity-reported: 100 mcg, subcutaneous injection |
Published-research dosing is what was given in the cited studies (species and units as reported). Community-reported dosing is what users describe, not from clinical studies. Neither is a recommendation. Not medical advice.
Where each point comes from: Clinicalhuman trials and FDA labels Lab / animalrodent, cell and ex vivo studies Community-reporteduser experience and commonly used protocols, not from clinical studies
In plain terms: It binds myostatin and related proteins that limit muscle growth, based on animal work. Proposed mechanism, from animal work: binds and neutralizes myostatin, activin and related growth inhibitors of the TGF-β family. Muscle-specific transgenic expression of human follistatin-344 increased skeletal muscle mass in pigs (Chang 2017). No approved pharmaceutical formulation of follistatin exists (Reichel 2019).
How to read this: Each item below is an effect observed in research subjects in the cited studies — think of Dexter, our stand-in research subject. These are findings from the literature, not results you should expect, and not medical advice.
Community-reportedUsers have reported 100 mcg (subcutaneous injection). This is not a recommendation.
Side effects reported in studies are listed separately below.
Community reports are anecdotal, vary widely in product quality and purity, and are not medical advice. Talk to a licensed provider.
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| Peptide | Half-Life | Route | Research Status |
|---|---|---|---|
| Follistatin 344 | Unknown | Subcutaneous injection | Preclinical (animal) |
| ACE-031 | ~12 days | Subcutaneous injection | Discontinued |
| IGF-1 DES | No published PK data found (des(1-3)IGF-I clears more rapidly than IGF-I in pigs/marmosets, but no published t1/2 value was found) | Intramuscular (site-specific) | Preclinical (animal) |
| IGF-1 LR3 | No published PK data found | Subcutaneous or intramuscular | Preclinical (animal) |
| MGF (Mechano Growth Factor) | No published PK data found | Intramuscular (site-specific) | Preclinical (animal) |
Values reflect figures reported in published research. Compare any peptides side-by-side →
This peptide belongs to the Muscle category. View All Muscle Peptides
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Dosing, half-life figures, and mechanism descriptions on this page are compiled from peer-reviewed published research, with the species and study type stated where reported. Figures labeled “Dosing used in published research” describe what was given in those studies and do not constitute dosing recommendations for any human use. Each cited paper is listed with DOI and PubMed links in the References section above. Found an error? Contact us.