Follistatin Dosage Guide

Follistatin is a single-chain glycoprotein that binds and neutralizes members of the TGF-β superfamily, most notably myostatin (GDF-8) and activin A. Myostatin is the primary negative regulator of skeletal muscle growth — by inhibiting myostatin, follistatin effectively removes the "brake" on muscle development.

The most commonly used research variants are Follistatin-344 (FS-344, the full-length precursor that converts to FS-315 and FS-303 in vivo) and Follistatin-315 (the circulating form). Animal models with myostatin deletions or follistatin overexpression demonstrate dramatic increases in muscle mass (2–3x normal), illustrating the pathway's profound influence on body composition.

Follistatin dosing data is limited and primarily derived from animal studies and gene therapy research:

Note: Follistatin research dosing in humans is largely extrapolated from animal data and anecdotal protocols. No human clinical trials have established optimal dosing for injectable follistatin. Conservative dosing with short cycles is strongly recommended.

Follistatin is typically administered once daily via subcutaneous injection:

• Morning injection: Most common timing, though no specific advantage over other times has been established.
• Post-training: Some protocols administer follistatin after exercise to coincide with the anabolic window.

Cycling: Follistatin cycles are intentionally short: 10–30 days on, followed by an extended break of at least 30–60 days. The short cycle duration reflects both the limited safety data and the theoretical concern that prolonged myostatin suppression may have adverse effects on cardiac and other tissues where myostatin plays regulatory roles.

• Step 1: Swab vial stoppers with alcohol.
• Step 2: For a 1 mg vial, add 1 mL BAC water to yield 1 mg/mL (100 mcg per 0.1 mL).
• Step 3: Direct the stream against the glass wall gently.
• Step 4: Allow the powder to dissolve naturally. Follistatin is a large protein — dissolution may take several minutes.
• Step 5: Store at 2–8°C. Use within 14 days. Follistatin is less stable than smaller peptides.

Administer subcutaneously using a 29–31 gauge insulin syringe. Handle reconstituted follistatin gently — as a large glycoprotein, it is sensitive to temperature changes and mechanical stress.

• 50–100 mcg/day: Limited data. Mild injection site reactions may occur.
• 100–200 mcg/day: Anecdotal reports of increased appetite, mild joint discomfort, and accelerated hair growth.
• 200–300 mcg/day: Potential for more pronounced effects. Theoretical concerns include disruption of follicle-stimulating hormone (FSH) signaling (as follistatin also inhibits activin, which regulates FSH), potentially affecting reproductive function.

Long-term concerns: Myostatin plays protective roles in cardiac tissue and tendons. Chronic suppression may increase the risk of cardiac hypertrophy and tendon fragility, though this has not been confirmed in short-term research protocols.

Follistatin is an experimental research compound with no FDA approval and extremely limited human data.

The consequences of systemic myostatin inhibition in humans are not fully understood. Potential risks include disruption of reproductive hormones (FSH/LH), cardiac complications from unchecked muscle growth, and tendon vulnerability. Use only in supervised research settings with appropriate monitoring. Cycles must be kept short.