HGH Fragment 176-191 is a synthetic peptide corresponding to the C-terminal portion (amino acids 176-191) of human growth hormone. This 16-amino acid fragment was identified as the region of GH responsible for its lipolytic (fat-burning) activity. It was studied for its ability to promote fat loss without the diabetogenic, growth-promoting, or IGF-1-stimulating effects of full-length GH. A stabilized analog, AOD-9604, reached Phase III clinical trials but failed to demonstrate sufficient efficacy for obesity. WADA bans this peptide.
Category: Growth Hormone Fragment. Evidence rating: D (animal/preclinical only).
Clinical status: Preclinical. The stabilized analog AOD-9604 completed Phase III for obesity but failed primary efficacy endpoints.
HGH Fragment 176-191 mimics the lipolytic action of the C-terminal loop of growth hormone. It stimulates lipolysis (fat breakdown) and inhibits lipogenesis (fat formation) in adipose tissue, reportedly through a mechanism independent of the GH receptor and without activating IGF-1 production.…
Safety considerations: Limited human safety data (mainly from AOD-9604 trials); AOD-9604 clinical trials reported no significant safety concerns at studied doses; No effect on blood glucose or insulin in available data.
Reviewed by the PeptideAtlas Editorial Team. Last reviewed: 2026-07-05.
HGH Fragment 176-191 is the native C-terminal sequence (amino acids 176-191) of human growth hormone. AOD-9604 is a stabilized, modified version of this fragment with improved stability. AOD-9604 advanced further in clinical development but ultimately failed Phase III trials for obesity.
Animal and in vitro data show genuine lipolytic activity. However, the stabilized analog AOD-9604 failed to demonstrate significant weight loss in a large Phase III clinical trial. This suggests that the fat-loss effects seen in preclinical models may not translate to clinically meaningful results in humans.
No. Fragment 176-191 does not activate the GH receptor in the same way as full-length GH and does not stimulate IGF-1 production. Its mechanism is limited to direct effects on adipose tissue.