MK-677 is not a peptide, and other things people get wrong

Two corrections that come up constantly. First, MK-677 (ibutamoren) is not a peptide at all; it is an orally active small molecule that mimics ghrelin at the GHS-R1a receptor. Second, despite years of trials it was never FDA approved.

The older-adult trial raised GH, IGF-1, and lean mass but did not establish a functional benefit, and the appetite and insulin-sensitivity effects are real considerations. It gets discussed here because it sits in the secretagogue conversation, not because it is a peptide.