Follistatin 315 vs MGF (Mechano Growth Factor)
Side-by-side comparison of key properties, dosing, and research.
Anabolic & IGF
Follistatin 315Anabolic & IGF
MGF (Mechano Growth Factor)- Summary
- Follistatin 315 is a splice variant isoform of follistatin produced by alternative mRNA processing. Unlike Follistatin 344 which is tethered to cell surfaces via heparan sulfate proteoglycans, FST-315 circulates freely in the bloodstream and has broader systemic distribution. It is the predominant circulating form and exerts systemic myostatin inhibition as well as FSH suppression, making it relevant to both muscle growth and reproductive endocrinology.
- MGF (Mechano Growth Factor) is a splice variant of IGF-1 that is locally produced in muscle tissue in response to mechanical damage from exercise. It activates muscle satellite cells (stem cells) to proliferate and repair damaged fibers, making it specifically targeted at exercise-induced hypertrophy.
- Half-Life
- ~3–5 hours (longer systemic circulation vs FST-344)
- Native MGF: minutes. PEG-MGF: ~3 days
- Admin Route
- SubQ, IM
- SubQ, IM
- Research
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- Typical Dose
- No established human dosing protocol
- 200–400 mcg
- Frequency
- Research use only
- 1–2 times per week
- Key Benefits
- Systemic myostatin inhibition for whole-body muscle growth
- Freely circulating — broader tissue distribution than FST-344
- Strong FSH-suppressive activity useful in certain hormonal protocols
- Potential for greater anabolic effect across multiple muscle groups simultaneously
- May be more relevant to reproductive endocrinology applications
- Studied in gene therapy approaches for muscular dystrophy
- Activates muscle satellite cells for repair and growth
- Accelerates recovery from muscle damage
- Synergistic with IGF-1 LR3 (different mechanisms)
- Promotes muscle hypertrophy specifically at exercised muscles
- Faster recovery between training sessions
- Potential for injury repair in connective tissue
- Side Effects
- Systemic FSH suppression — significant concern for fertility
- Greater potential for off-target effects vs FST-344 due to systemic distribution
- Limited human safety data
- Potential cardiac hypertrophy with prolonged high-dose exposure
- Muscle soreness (satellite cell activation)
- Injection site irritation
- Hypoglycemia risk (modest, less than IGF-1 LR3)
- Stacks With
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