Follistatin 315 vs Semaglutide
Side-by-side comparison of key properties, dosing, and research.
Anabolic & IGF
Follistatin 315GLP-1 / Weight Loss Agonists
Semaglutide- 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.
- Semaglutide is an FDA-approved GLP-1 receptor agonist originally developed for type 2 diabetes that has proven remarkably effective for weight loss. Clinical trials show average 15–20% body weight reduction. It is marketed as Ozempic (diabetes) and Wegovy (weight management).
- Half-Life
- ~3–5 hours (longer systemic circulation vs FST-344)
- ~7 days
- Admin Route
- SubQ, IM
- SubQ, Oral
- Research
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- Typical Dose
- No established human dosing protocol
- 0.25 mg → 0.5 mg → 1 mg → 1.7 mg → 2.4 mg
- Frequency
- Research use only
- Once weekly, subcutaneous
- 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
- Average 15–20% body weight reduction in clinical trials (STEP trials)
- Significant reduction in appetite and food cravings
- Improvement in blood sugar control and insulin sensitivity
- Reduces cardiovascular risk (SELECT trial: 20% reduction in MACE)
- May reduce risk of kidney disease
- Improves metabolic markers (cholesterol, blood pressure)
- FDA-approved — extensively studied with robust safety data
- Weekly dosing convenience
- 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, especially during titration)
- Vomiting
- Diarrhea or constipation
- Abdominal discomfort
- +4 more
- Stacks With
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