Follistatin
Monograph · DFollistatin / FST-344
Endogenous myostatin + activin binding protein. Inhibits myostatin → drives skeletal-muscle hypertrophy + body-comp shift. Grey-market peptide (FST-344) is the synthetic analog of the 344-aa serum isoform.
How it clearsHalf cleared in ~2d. Most (~96%) gone by ~8d.
Compare these compounds
Mechanism, evidence, legal path, cost — all side-by-side.
This compound sits in research-grey territory. The caveats below carry more weight than for FDA-approved entries — read them.
Acrush in interest after Bryan Johnson's Oct 2023 follistatin gene-therapy experiment (BioViva-style AAV vector). Grey-market injectable peptide form (FST-344) emerged in 2024-25 to satisfy the spillover demand. Mouse + non-human-primate data documents 15-40% muscle-mass gain over 8-12 weeks. Zero published human RCT of injectable FST-344. The gene-therapy version (single-dose AAV) is a completely different risk profile from the daily/weekly peptide protocol biohackers run.
Limited human data. The mechanism touches a sensitive regulatory axis, which means effects — when they appear — tend to be more pronounced than in other categories. Both undershoot and overshoot are real outcomes here. This is the tier where tracking matters most and flying blind costs most.
Zero published human RCT of injectable FST-344. Mouse + primate data drove the hype + Bryan Johnson's experiment publicized it. Long-term myostatin suppression has un-modeled cardiac + tendon-rigidity concerns. Identity verification of grey-market product is poor. Don't conflate the gene-therapy version (single-dose AAV) with the daily/weekly peptide.
Upload your data to see how it relates to Follistatin.
Upload a lab file (LabCorp / Quest) or DNA file (23andMe / AncestryDNA). Stack will show your specific markers alongside the literature-reported response windows.
Upload in /historyPer-claim grading. Each claim is graded independently — same peptide, different claims can carry different grades.
- DMechanistic / anecdotal
Follistatin-344 gene-therapy claims exceed injectable peptide evidence
1 supporting referencesVerified 31d ago
External links to PubMed searches, ClinicalTrials.gov, and FDA materials. We do not host papers — we point at canonical sources.
Research-grey · no FDA pathway · gene-therapy version is investigational
Pre-filled with this compound's published dose range: 100-500 mcg · 2-3× weekly, subcutaneous
Calculator is a discussion tool. Verify reconstitution + dosing with a qualified provider. Stack is not a prescription source. Use sterile technique and inspect every vial.
No field reports yet
Field reports are added as users share their real-world protocols.
Next visit & citations
Handoff & sources
Running this compound? Log it in /history, then open Dr Passport before your visit. Methodology explains grades; the research dashboard sorts the full catalog with citations.