What Is HGH Fragment 176-191?
HGH Fragment 176-191 (“Frag 176-191”) is a synthetic peptide corresponding to the last 16 amino acids (residues 176-191) of the C-terminal region of human growth hormone (hGH) — the part of the molecule associated with fat metabolism. It is sold and used experimentally (typically by subcutaneous injection) as a “fat-loss” peptide, on the theory that this fragment keeps growth hormone’s lipolytic (fat-burning) action while lacking its growth-promoting and blood-sugar effects. It is a research chemical, not an approved medicine or dietary supplement, and essentially all of the published evidence is preclinical.
Evidence
The relevant published research is on the hGH C-terminal lipolytic domain, most of it conducted on the closely related analogue AOD-9604 (Frag 176-191 with an added N-terminal tyrosine), not on Frag 176-191 itself. In obese rats, oral treatment with this synthetic lipolytic domain reduced body-weight gain and increased lipolytic activity in adipose tissue without the insulin-desensitising effect of intact growth hormone 1Reference 1AnimalMetabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone — rat (in vivo) studyView study →. Follow-up work in obese and β3-adrenoceptor knockout mice examined its effects on lipid metabolism and adiposity 2Reference 2AnimalThe effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism following chronic treatment in obese mice and β3-AR knock-out mice — mouse (in vivo) studyView study →. These are animal findings, and they do not establish that Frag 176-191 causes meaningful fat loss, or is safe, in humans. I did not find any human efficacy trial of HGH Fragment 176-191 itself in this pass — its widely marketed fat-loss claims rest on animal data and on read-across from AOD-9604, not on human trials of this specific peptide.
Dosage & Safety
There is no established human dose for HGH Fragment 176-191; the injection regimens circulating online are not derived from controlled human trials, and this page makes no dosing recommendation. It is not approved by the FDA or other regulators as a drug or dietary supplement, and growth-hormone fragments of this type are prohibited in sport as non-approved substances. Human safety, long-term effects, drug interactions, and pregnancy/lactation safety are not established / not assessed in this pass. This entry is informational only and is not an endorsement of use.
References
- Ng FM, et al. (2000). Metabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone — rat (in vivo) study. Horm Res. https://pubmed.ncbi.nlm.nih.gov/11146367/
- Heffernan MA, et al. (2001). The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism following chronic treatment in obese mice and β3-AR knock-out mice — mouse (in vivo) study. Endocrinology. https://pubmed.ncbi.nlm.nih.gov/11713213/