Quick answer: what is HGH Fragment 176-191?
HGH Fragment 176-191 is a synthetic piece of the tail end of the growth-hormone molecule, marketed as a fat-loss peptide.
Quick facts
- Class
- Growth-hormone C-terminal fragment
- Related to
- AOD-9604 (a modified, stabilized version)
- Studied for
- Fat metabolism / lipolysis (animal models)
- Evidence level
- Preclinical; no convincing human fat-loss data
- Approval
- Not FDA-approved; sold as a research chemical
- Derived from
- C-terminus of growth hormone (residues 176-191)
- Related compound
- AOD-9604
- Human evidence
- None convincing (AOD-9604 trials negative)
Key takeaways
- It was designed to reproduce growth hormone's fat-burning effect without its growth or blood-sugar effects — but this is shown mainly in animals.
- It is closely related to AOD-9604, a stabilized version that failed to beat placebo for weight loss in human trials.
- It is not FDA-approved, is sold as a research chemical, and is banned in sport.
Overview
HGH Fragment 176-191 is a short synthetic peptide corresponding to the final amino acids (176 to 191) of the growth-hormone molecule. Researchers isolated this region after finding that it carried growth hormone's fat-reducing activity while leaving out the parts responsible for growth and for raising blood sugar.[1][3]
It is closely related to AOD-9604, which is essentially a stabilized, modified version of this same fragment. Like AOD-9604, it is popular in fitness marketing for "fat loss" but is not an approved drug and lacks convincing human evidence.
How it works
In laboratory and animal studies, the fragment appears to stimulate lipolysis (the breakdown of stored fat) and to inhibit lipogenesis (the formation of new fat), mimicking this specific action of full growth hormone.[1][4] Importantly, it was reported to do so without the growth-promoting or insulin-resistance effects of GH, which was the rationale for developing it.
How well any of this translates to fat loss in humans is unknown, because the mechanism is established mainly in rodent tissue and obese-mouse models.[2]
Research & evidence
The supporting research is preclinical. Early work characterized a lipolytic domain in the C-terminal region of growth hormone, and studies in obese mice reported increased fat oxidation and weight loss with the fragment or closely related sequences.[2][4]
The better-studied descendant, AOD-9604, advanced into human trials as an anti-obesity candidate and ultimately failed to produce meaningful weight loss beyond placebo. That outcome is the most relevant human signal available, and it argues against the fat-loss claims made for this fragment. Robust human trials of HGH Fragment 176-191 itself do not exist.
Safety & legal status
Human safety data are essentially absent, so the risk profile is unquantified rather than reassuring. As with any research chemical, products sold online are not quality-assured for purity or sterility. HGH Fragment 176-191 is not FDA-approved for any use, is sold only as a research chemical, and growth-hormone-related peptides are prohibited in sport by WADA.
Frequently asked questions
Does HGH Fragment 176-191 actually burn fat?
In animal and laboratory studies it stimulates fat breakdown and reduces fat formation, but this has not been demonstrated in humans. Its close relative AOD-9604 reached human obesity trials and failed to produce meaningful weight loss beyond placebo, which argues against the fat-loss claims.
What is the difference between HGH Fragment 176-191 and AOD-9604?
AOD-9604 is essentially a modified, stabilized version of the same C-terminal growth-hormone fragment. AOD-9604 has been studied more, including in human trials, while HGH Fragment 176-191 itself has no convincing human evidence.
Is HGH Fragment 176-191 legal or approved?
No. It is not FDA-approved for any use and is sold only as a research chemical, which is not quality-assured for purity or sterility. As a growth-hormone-related peptide, it is also prohibited in sport by WADA.
Is HGH Fragment 176-191 the same as HGH?
No. It is only a small fragment of the growth-hormone molecule, chosen for its fat-metabolism activity. It does not reproduce the full effects of growth hormone and is not a form of HGH therapy.
References
Each source links to its original record — peer-reviewed studies, regulator pages, or reference texts, labelled by type. We summarize findings neutrally; a citation is a reference, not an endorsement, and not a claim that its authors reviewed this page.
- Ng FM, Sun J, Sharma L, et al. Metabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone. Horm Res. 2000. Peer-reviewed study
- Heffernan MA, Thorburn AW, Fam B, et al. Increase of fat oxidation and weight loss in obese mice caused by chronic treatment with human growth hormone or a modified C-terminal fragment. Int J Obes Relat Metab Disord. 2001. Peer-reviewed study
- Wu Z, Ng FM. Antilipogenic action of synthetic C-terminal sequence 177-191 of human growth hormone. Biochem Mol Biol Int. 1993. Peer-reviewed study
- Ng FM, Jiang WJ, Gianello R, et al. Molecular and cellular actions of a structural domain of human growth hormone on lipid metabolism in Zucker fatty rats. J Mol Endocrinol. 2000. Peer-reviewed study