Follistatin vs MK-677 (Ibutamoren)

A detailed comparison to help you understand the differences and choose the right peptide for your research goals.

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.

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MK-677 (Ibutamoren)

MK-677, also known as Ibutamoren, is an orally active growth hormone secretagogue. Unlike peptides, it can be taken orally and has a long half-life, providing 24-hour GH elevation.

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Side-by-Side Comparison

Aspect	Follistatin	MK-677 (Ibutamoren)
Dose Range	50 mcg–100 mcg	10 mg–25 mg
Frequency	1x daily	1x daily
Cycle Length	2–4 weeks	8–24 weeks
Route	subcutaneous	oral
Mechanism	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.	Acts as a potent, selective agonist of the ghrelin receptor (GHS-R1a). Increases GH and IGF-1 levels without affecting cortisol. Mimics ghrelin's GH-releasing effects.
Typical Dosage	Research protocols typically use 100-300mcg daily, though optimal dosing is not well established. Gene therapy approaches have also been studied.	Typical dosing: 10-25mg taken orally once daily. Often taken at night due to sleep benefits and appetite increase.
Administration	Subcutaneous injection. Different isoforms exist (FS344, FS315) with varying properties. Requires careful sourcing due to complexity.	Oral administration (capsule or liquid). Can be taken with or without food. Long half-life allows once-daily dosing.
Side Effects	Limited human data. Theoretical concerns about effects on other organs where activin signaling is important.	Increased appetite and water retention are most common. May cause lethargy, vivid dreams, and mild numbness. Can affect blood glucose and insulin sensitivity.
Best For	Muscle Growth	Muscle Growth Fat Loss Recovery & Healing Sleep Quality