Follistatin 315 vs Mazdutide
Side-by-side comparison of key properties, dosing, and research.
Anabolic & IGF
Follistatin 315GLP-1 / Weight Loss Agonists
Mazdutide- 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.
- Mazdutide is a once-weekly GLP-1/glucagon dual receptor agonist developed by Innovent Biologics and Eli Lilly. Phase 2 trials in Chinese populations demonstrated up to 11.3% body weight reduction at 6 mg over 24 weeks. It also improves liver fat, glycemic control, and lipid profiles. Phase 3 trials are ongoing primarily in China.
- Half-Life
- ~3–5 hours (longer systemic circulation vs FST-344)
- ~7 days
- Admin Route
- SubQ, IM
- SubQ
- Research
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- Typical Dose
- No established human dosing protocol
- 1.5 mg → 3 mg → 4.5 mg → 6 mg
- Frequency
- Research use only
- Once weekly
- 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
- Up to 11.3% body weight reduction at 24 weeks (Phase 2, 6 mg dose)
- Significant reduction in liver fat content (NAFLD/MASH potential)
- Improves HbA1c and fasting glucose in type 2 diabetes
- Favorable lipid profile changes (reduced triglycerides)
- Once-weekly subcutaneous dosing
- Potential for superior weight loss vs GLP-1 monotherapy
- 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
- Nausea
- Vomiting
- Decreased appetite
- Diarrhea
- +3 more
- Stacks With
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