Follistatin 344

Description

FST-344, or Follistatin-344, is a protein precursor studied for its ability to regulate muscle growth. “344” refers to its 344 amino acids; after processing, it produces the circulating form called follistatin-315. Follistatin binds signaling proteins—including myostatin and activin—that help control muscle development. In simple terms, it can reduce some of the biological signals that limit muscle growth. Follistatin research⁠

Its potential benefits being studied include:

• Increased muscle mass: Animal studies found larger muscle fibers after follistatin gene delivery.
• Improved muscle strength: Some animal studies demonstrated gains in strength alongside muscle growth.
• Support for muscle-wasting disorders: Researchers are investigating whether it could help preserve muscle and physical function in conditions such as muscular dystrophy. Preclinical study⁠

The human evidence is limited. A small trial involving six people with Becker muscular dystrophy reported improved walking distance in some participants. However, it used gene therapy that instructed muscle cells to produce follistatin, which is very different from injecting a commercially sold FST-344 vial. Those results do not establish benefits or safety for those products. Human clinical trial⁠

FST-344 should therefore be described as an experimental muscle-growth research protein, with potential benefits rather than proven bodybuilding, recovery, or anti-aging effects. Because follistatin also affects activin signaling, its effects extend beyond muscle, and long-term safety remains uncertain.