Follistatin vs Mechano Growth Factor (MGF)
Two elegant muscle-growth mechanisms whose most impressive data belong to gene therapy and to your own genes, not to the injectable vials sold under their names.
Short answer
Both rest mostly on animal and lab work, so the evidence cannot separate follistatin from MGF. What does differ is access, since follistatin is legitimately available only inside clinical trials, while MGF is sold gray-market as a research chemical. Follistatin is the one sold for muscle growth, while MGF targets muscle growth and recovery.
Follistatin
FST-344
Blocking myostatin drives dramatic muscle growth in mice and primates, but the injectable follistatin peptide has no controlled human efficacy trials.
Full Follistatin evidence reviewMechano Growth Factor (MGF)
IGF-1Ec / PEG-MGF
A real load-induced IGF-1 splice variant in muscle biology, but the injected PEG-MGF product has no controlled human outcome trials.
Full Mechano Growth Factor (MGF) evidence reviewFollistatin vs Mechano Growth Factor (MGF): head to head
- FDA status / approved use
Follistatin
Not FDA-approved for any use; gene therapy only in small early-phase trials for muscle diseasesMechano Growth Factor (MGF)
Unapproved research-grade peptide, not an approved medicine- Marketed for
Follistatin
Muscle growthMechano Growth Factor (MGF)
Muscle growth, recovery- Outcome areas
Follistatin
Muscle / strength / lean massMechano Growth Factor (MGF)
Muscle / strength / lean mass; Injury recovery / tissue repair- Evidence grade
Follistatin
Preclinical / minimalMechano Growth Factor (MGF)
Preclinical / minimal- How it works
Follistatin
Binds and neutralizes myostatin, the body's built-in brake on muscle sizeMechano Growth Factor (MGF)
Load-induced IGF-1 variant that pushes muscle satellite cells to multiply- Route and dosing
Follistatin
Injected peptide; studied clinically only as intramuscular gene therapyMechano Growth Factor (MGF)
Injection, usually as pegylated PEG-MGF; no established dose- Headline human result
Follistatin
Not establishedMechano Growth Factor (MGF)
Not established- Strongest evidence
Follistatin
Kota, Sci Transl Med 2009 (primates). Little or no controlled human outcome data for the marketed useFollistatin evidence reviewPubMed 20368179Mechano Growth Factor (MGF)
Yang & Goldspink, FEBS Lett 2002. Little or no controlled human outcome data for the marketed useMechano Growth Factor (MGF) evidence reviewPubMed 12095637- Key safety signal
Follistatin
Blunts body-wide signaling in the ovary, pituitary and fibrosis; long-term human safety unknownMechano Growth Factor (MGF)
No human safety data or established dose; promotes cell growth; vial contents unverified- How it is obtained
Follistatin
Legitimately available only inside clinical trials; vials sold online are gray-market research chemicalsMechano Growth Factor (MGF)
Sold gray-market as a research chemical; no approved or legitimately compounded human product
| Follistatin | Mechano Growth Factor (MGF) | |
|---|---|---|
| FDA status / approved use | Not FDA-approved for any use; gene therapy only in small early-phase trials for muscle diseases | Unapproved research-grade peptide, not an approved medicine |
| Marketed for | Muscle growth | Muscle growth, recovery |
| Outcome areas | Muscle / strength / lean mass | Muscle / strength / lean mass; Injury recovery / tissue repair |
| Evidence grade | Preclinical / minimal | Preclinical / minimal |
| How it works | Binds and neutralizes myostatin, the body's built-in brake on muscle size | Load-induced IGF-1 variant that pushes muscle satellite cells to multiply |
| Route and dosing | Injected peptide; studied clinically only as intramuscular gene therapy | Injection, usually as pegylated PEG-MGF; no established dose |
| Headline human result | Not established | Not established |
| Strongest evidence | Kota, Sci Transl Med 2009 (primates). Little or no controlled human outcome data for the marketed useFollistatin evidence reviewPubMed 20368179 | Yang & Goldspink, FEBS Lett 2002. Little or no controlled human outcome data for the marketed useMechano Growth Factor (MGF) evidence reviewPubMed 12095637 |
| Key safety signal | Blunts body-wide signaling in the ovary, pituitary and fibrosis; long-term human safety unknown | No human safety data or established dose; promotes cell growth; vial contents unverified |
| How it is obtained | Legitimately available only inside clinical trials; vials sold online are gray-market research chemicals | Sold gray-market as a research chemical; no approved or legitimately compounded human product |
marks a row where the two differ. “Not established” marks a cell the available evidence does not answer. Evidence grades come from our evidence matrix, which grades each molecule on the human data for the use it is marketed for.
- Preclinical / minimal:
- Evidence is largely animal, in-vitro, or anecdotal. Little or no controlled human outcome data for the marketed use.
Our verdict
Neither injectable has controlled human efficacy data, so the honest comparison is about which borrowed evidence each one leans on. Follistatin sits on a real pathway: it neutralizes myostatin, the body's brake on muscle, and the striking results come from gene therapy, where AAV-delivered follistatin grew muscle and strength in monkeys and reached small, open-label early-phase human trials in Becker muscular dystrophy and inclusion body myositis. The gray-market follistatin-344 peptide is a different proposition, cleared in hours, unable to recreate sustained local expression, and untested in controlled human trials; follistatin also blunts activin and other TGF-beta ligands that do real work outside muscle, so systemic use has unknown long-term safety. MGF's human evidence is likewise displaced: it documents the body's own IGF-1Ec splice variant upregulating after resistance exercise, not anyone injecting PEG-MGF. Both injectables are unapproved research-only material with no established dose.
Follistatin fits if
Follistatin is the more instructive read if you want to see how genuinely serious translational science, in this case gene therapy in an investigational setting, gets repackaged as a consumer vial it never tested.
Mechano Growth Factor (MGF) fits if
MGF is the more instructive read if you want the cleanest example of the endogenous-versus-injected swap, where the real human finding argues for training rather than for buying anything.
Follistatin vs Mechano Growth Factor (MGF): common questions
- Is either follistatin or MGF FDA-approved?
- No. Follistatin is not FDA-approved for any use; gene therapy only in small early-phase trials for muscle diseases. MGF is an unapproved research-grade peptide, not an approved medicine.
- Which has stronger human evidence, follistatin or MGF?
- Neither. Both are graded preclinical / minimal, with little or no controlled human outcome data for the marketed use. The key source for follistatin is Kota, Sci Transl Med 2009 (primates); for MGF, it is Yang & Goldspink, FEBS Lett 2002.
- What are the main safety concerns with follistatin and MGF?
- Follistatin blunts body-wide signaling in the ovary, pituitary and fibrosis; long-term human safety unknown. MGF has no human safety data or established dose; promotes cell growth; vial contents unverified.
Key studies behind each
Follistatin
- McPherron AC, Lawler AM, Lee SJ. (1997). Regulation of skeletal muscle mass in mice by a new TGF-beta superfamily member. Nature. PubMed 9139826
- Lee SJ, McPherron AC. (2001). Regulation of myostatin activity and muscle growth. Proc Natl Acad Sci U S A. PubMed 11459935
- Lee SJ. (2007). Quadrupling muscle mass in mice by targeting TGF-beta signaling pathways. PLoS One. PubMed 17726519
- Kota J, Handy CR, Haidet AM, Montgomery CL, Eagle A, et al. (2009). Follistatin gene delivery enhances muscle growth and strength in nonhuman primates. Sci Transl Med. PubMed 20368179
Mechano Growth Factor (MGF)
- Goldspink G. (2005). Mechanical signals, IGF-I gene splicing, and muscle adaptation. Physiology (Bethesda). PubMed 16024511
- Yang SY, Goldspink G. (2002). Different roles of the IGF-I Ec peptide (MGF) and mature IGF-I in myoblast proliferation and differentiation. FEBS Lett. PubMed 12095637
- Hameed M, Orrell RW, Cobbold M, Goldspink G, Harridge SD. (2003). Expression of IGF-I splice variants in young and old human skeletal muscle after high resistance exercise. J Physiol. PubMed 12562960
- Ates K, Yang SY, Orrell RW, Sinanan AC, et al. (2007). The IGF-I splice variant MGF increases progenitor cells in ALS, dystrophic, and normal muscle. FEBS Lett. PubMed 17531227
The full evidence reviews
- Follistatin: an elegant muscle mechanism, proven mostly in mice and gene therapy
Follistatin neutralizes myostatin, the body's brake on muscle — and the growth data are real. But they come from mice, monkeys, and gene therapy, not from the injectable 'follistatin-344' peptide sold online, which has no controlled human efficacy trials.
Updated August 2026
- Mechano Growth Factor (MGF): real repair biology, no human proof for the injectable
MGF is IGF-1Ec — a splice variant your muscle makes after loading, and a genuine satellite-cell signal in cell and animal models. But the human data is about your own gene switching on with exercise, not about injecting PEG-MGF, which has no human outcome trials at all.
Updated August 2026
Where to get it
Where to get peptide therapy
Clinician-led telehealth services that prescribe compounded peptides. The specific peptides offered vary by provider — confirm Follistatin availability before ordering.
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