Follistatin and ACE-031 are the best-known agents in the myostatin-inhibitor category, discussed for their potential to remove a natural brake on muscle growth. Myostatin, a member of the activin/TGF-beta family, limits how much muscle the body builds; block it and animal models grow dramatically muscular. Follistatin is a natural protein that binds and neutralises myostatin, and follistatin-344 is a peptide sold on that premise, while ACE-031 was an engineered decoy activin receptor developed as a drug candidate.
This is a harm-reduction tracking guide, not a recommendation - and this class deserves particular caution. Human evidence for physique benefit is essentially absent, the compounds are experimental and expensive, and the market is riddled with mislabelled or underdosed products. ACE-031's own clinical development was halted after trials surfaced vascular and bleeding-related side effects, which is a serious warning about interfering with this pathway systemically. If you have already decided to use one, the goal here is to log carefully and stay alert to harm.
What they are
- Follistatin (e.g. follistatin-344): a natural myostatin-binding protein sold as an injectable research peptide
- ACE-031: a decoy soluble activin receptor type IIB that mops up myostatin and related ligands; a former pharmaceutical candidate, not an approved drug
- Both aim at the same outcome - releasing the myostatin/activin brake on muscle - but hit the pathway at different points and with different reach
The honest picture
- The spectacular muscle growth is a mouse and livestock phenomenon; it has not translated to proven, safe physique gains in humans
- ACE-031 trials were stopped over safety signals including nosebleeds, gum bleeding, and dilated blood vessels, reflecting how broadly activin-receptor blockade acts in the body
- The activin/TGF-beta family regulates far more than muscle - blood vessels, reproduction, and other tissues - so off-target effects are a real, not theoretical, concern
- Product quality is a major problem: many vials sold as follistatin are mislabelled, degraded, or underdosed
Typical protocol shape
- Protocols circulating in user communities are experimental and not validated; there is no established safe or effective regimen
- Because human dosing evidence is absent, any range you see is extrapolation, not literature-backed guidance
- Verification of what is actually in the vial (third-party testing) is more relevant here than any dosing scheme
What to track daily
- Compound, source, batch, dose, and injection details
- Any bruising, nosebleeds, bleeding gums, or unusual vascular signs - these mirror the ACE-031 trial concerns and warrant stopping
- Injection-site reactions, since biologic peptides can be immunogenic
- Subjective energy, recovery, and any systemic symptoms
What to track weekly
- Bodyweight, key circumferences, and strength on fixed lifts
- Standardised physique photos under identical conditions
- Whether any change tracks the compound or your training and diet, which usually explain most of it
Bloodwork worth doing
- A baseline and periodic complete blood count and coagulation markers, given the bleeding signals seen with activin-pathway blockade
- Liver and kidney panels to catch systemic strain
- Understand that no bloodwork panel makes an unproven experimental biologic safe; it only helps catch harm sooner
Realistic expectations
- The realistic expectation is that you may spend a lot of money on a mislabelled product with no reliable benefit
- Human results, if any, are far removed from the animal-model imagery used to sell these
- Training, nutrition, and sleep remain the levers with actual evidence behind them
Common mistakes
- Believing the mouse-muscle marketing and expecting comparable human results
- Trusting vial labels without any third-party verification
- Ignoring early bleeding or vascular symptoms that echo the trial-halting side effects
- Attributing normal training progress to the compound
Safety notes
This is an experimental, unapproved class whose lead drug candidate was pulled from development over vascular and bleeding side effects, and whose grey-market products are frequently not what the label claims. Interfering with the activin/TGF-beta pathway has body-wide consequences that are poorly characterised in humans. Anyone considering these should understand they are self-experimenting with a discontinued-for-safety mechanism, and should involve a physician and stop at the first sign of bleeding, bruising, or vascular symptoms.
Peptid AI is an educational and self-tracking tool. Nothing in this post is medical advice. Doses mentioned reflect what is commonly reported in research literature — they are not recommendations. Always consult a qualified physician before starting, changing, or stopping any protocol.