Follistatin 315 vs Survodutide
Side-by-side comparison of key properties, dosing, and research.
Anabolic & IGF
Follistatin 315GLP-1 / Weight Loss Agonists
Survodutide- 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.
- Survodutide is a once-weekly GLP-1/glucagon dual receptor agonist developed by Boehringer Ingelheim and Zealand Pharma. Phase 2 trials demonstrated up to 18.7% body weight reduction at 46 weeks, among the highest reported for a dual agonist. It is being studied for obesity and MASH (metabolic dysfunction-associated steatohepatitis), where the glucagon component drives hepatic fat clearance.
- 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
- 0.6 mg → 2.4 mg → 4.8 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 18.7% body weight reduction at 46 weeks (Phase 2)
- Strong MASH activity — Phase 3 SYNCHRONIZE-NASH trials ongoing
- Reduces hepatic fat content via glucagon receptor-driven liver oxidation
- Once-weekly subcutaneous injection
- Greater weight loss potential than GLP-1 monotherapy
- Improvements in liver fibrosis markers in early data
- 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 (most common during titration)
- Vomiting
- Diarrhea
- Decreased appetite
- +3 more
- Stacks With
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