An increase in lean mass is not automatically an increase in useful muscle function. Body-composition measures can reflect changes in water and other nonfat tissues as well as muscle. Research intended to support a muscle-building claim should therefore measure the outcome it actually promises.

A randomized study in healthy older men examined growth hormone, resistance exercise and muscle outcomes. The reported findings did not show added muscle strength or hypertrophy from growth hormone in the tested conditions. Growth hormone and strength in healthy older men This is not a direct study of every growth-hormone secretagogue, but it demonstrates why hormonal and body-composition signals cannot replace functional evidence.

For an experimental peptide, a useful outcome set might distinguish muscle size, strength, power, endurance and performance in daily activities. Each requires an appropriate measurement method. Changes should be compared with a relevant control and interpreted alongside training, nutrition and baseline health.

The study population is equally important. A treatment for a diagnosed deficiency cannot be assumed to enhance healthy athletes. Older adults, people recovering from illness and trained competitors may have different responses and risks. A mechanistic explanation involving growth signaling does not resolve those differences.

A credible report should also include adverse events, withdrawals and the duration of follow-up. More tissue on a scan is not sufficient if the intervention produces clinically important harm or the effect disappears without functional benefit.

This article offers no peptide ranking or performance protocol. It proposes an evidence standard: identify the compound, study the relevant population and measure the specific functional claim. Statements that a research peptide reliably builds muscle should remain unverified until controlled human evidence supports that conclusion for the actual product and use.