Follistatin
Follistatin is a glycoprotein that inhibits myostatin, the protein responsible for limiting muscle growth. By blocking myostatin, follistatin can theoretically allow for increased muscle development beyond natural limits.
Mechanism of Action
Binds to and neutralizes myostatin and activin, both of which are negative regulators of muscle mass. This removes the natural brake on muscle growth, allowing for enhanced hypertrophy.
Dosage Overview
Dose Range
50 mcg – 100 mcg
Route
subcutaneous
Frequency
1x daily
Cycle Length
2–4 weeks
Reconstitution
Typical Dosage (Research)
Research protocols typically use 100-300mcg daily, though optimal dosing is not well established. Gene therapy approaches have also been studied.
Subcutaneous injection. Different isoforms exist (FS344, FS315) with varying properties. Requires careful sourcing due to complexity.
Considerations for Men & Women
Women: Follistatin inhibits activin and myostatin. In women, activin plays roles in reproductive biology (FSH regulation, follicular development). Exogenous follistatin could theoretically affect menstrual cycling and fertility — use with caution. Contraindicated during pregnancy.
Men: Primarily researched for myostatin inhibition and muscle growth. Less reproductive concern than in women, though activin does play a role in spermatogenesis. Limited human data for both sexes.
Individual responses vary. These notes reflect general trends from research literature and are not medical advice.
Quick Calculator
Quick Calculator
Concentration: 1,000 mcg/ml
Volume to inject: 0.05 ml
Syringe units (U-100): 5.0 units
Pre-filled with Follistatin defaults. Adjust values as needed.
Side Effects & Risks
Limited human data. Theoretical concerns about effects on other organs where activin signaling is important.
Very limited human research. May affect reproductive function and other activin-dependent processes. Expensive and difficult to source.
Who Uses Follistatin
Researchers, advanced bodybuilders, those interested in myostatin inhibition.
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