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Not medical advice. The Atlas is not a substitute for a clinician who can examine you.

HGH Fragment 176-191

HGH C-Terminal Fat Metabolism Fragment

Evidence grade 1 of 5, Untested. Read how the Atlas grades evidence.

HGH Fragment 176-191 itself has no controlled human trials; it is marketed for fat loss on animal and in-vitro lipolysis data. Its near-identical analog AOD-9604 (the same C-terminal sequence with an added N-terminal tyrosine for stability) is the only version to reach controlled human testing, and its pivotal Phase 2b OPTIONS trial (536 subjects, 24 weeks, Metabolic Pharmaceuticals) failed to produce significant weight loss versus placebo, after which development for obesity was terminated in 2007. The marketed fat-loss claim is therefore refuted-adjacent rather than merely unproven, which places the fragment at grade 1.

FDA
No FDA-approved product. In the near-identical analog AOD-9604, the FDA proposed at the December 4, 2024 PCAC meeting not to include it on the 503A bulk drug substances list, citing insufficient safety and efficacy data, immunogenicity risk, and the absence of an approved application. The fragment itself is sold as an unapproved research chemical.
WADA
Prohibited at all times under class S2 (growth hormone fragments, named alongside AOD-9604 and hGH 176-191).

Reference only. Not medical advice.

What can go wrong

No FDA-approved product and no human trials of the fragment itself; the same-family analog AOD-9604 failed its pivotal Phase 2b obesity trial versus placebo; WADA-prohibited; gray-market purity and dosing.

Talk to a clinician before taking this. The Atlas can tell you what has been studied about HGH Fragment 176-191. It cannot tell you how it would interact with your body, your history, or anything else you are taking, and nothing on this page is a reason to start.

A C-terminal fragment of human growth hormone marketed for fat loss, essentially the same molecule as AOD-9604 aside from a stabilizing N-terminal tyrosine. AOD-9604 failed its pivotal Phase 2b obesity trial against placebo and was discontinued; the fragment itself has no human trials, no FDA-approved product, and is sold as an unapproved research chemical.

What people take it for

These are the reasons people give for taking it. They are not effects it has been shown to have.

  • Fat loss
  • Body recomposition

How it is supposed to work

HGH Fragment 176-191 is the small piece of growth hormone responsible for its fat-burning effect, isolated from the rest of the molecule. The idea, the same one behind AOD-9604, is to capture growth hormone’s ability to mobilize fat without its growth-promoting or blood-sugar effects. It is marketed for fat loss and used by injection in the gray market.

HGH Fragment 176-191 is literally the stretch of amino acids from position 176 to 191 at the tail end of human growth hormone. AOD-9604 is essentially this same fragment with a small stabilizing modification added for drug development, so the two are sold almost interchangeably, with AOD-9604 being the optimized clinical version of this bare fragment.

Type
HGH fragment
Region
Growth hormone 176-191
Optimized form
AOD-9604
Obesity trials
Failed
Approved
No
Sport
Prohibited

The Bare Fragment Behind AOD-9604, Same Failed Story

HGH Fragment 176-191 is, for practical purposes, the unpolished version of AOD-9604, and the AOD-9604 entry tells the real story. The appealing concept is genuine: this tail region of growth hormone seems to carry the lipolytic, fat-mobilizing activity without the growth and insulin-resistance effects of the whole hormone. The disappointing reality is also genuine: developed and tested as a weight-loss drug, the optimized version failed its obesity trials, showing no meaningful fat-loss benefit over placebo in humans, and it was never approved. The bare fragment sold in the gray market rides on that same failed clinical story, with even less standardization. It is a clever idea that did not work in people, repackaged as a fat-loss peptide.

Safety in detail

The marketed fat-loss positioning is associated with a molecule whose closest tested form, AOD-9604, showed no significant weight loss over placebo in a 536-subject Phase 2b trial, after which obesity development was halted. The fragment sold today has no controlled human safety or efficacy data of its own and is distributed as a research chemical not intended for human use.

  • The optimized version failed to show meaningful fat loss in humans, so efficacy is the core problem.
  • It is unapproved and sold gray-market, with sourcing and purity risk.
  • It is prohibited in sport.
  • Its profile rests on the AOD-9604 clinical record rather than its own trials.

Children and teenagers

HGH Fragment 176-191 has no validated pediatric use and is an unapproved injected peptide. There is no appropriate pediatric use.

What people get wrong

Nothing recorded here yet. There is almost certainly something people get wrong about this one, and the blank space means we have not written it down, not that the record is clean.

Who profits, and who pushes back

Nobody is named here yet, because we have not done that work on this entry. Read that as unfinished. Somebody almost certainly sells this, and somebody almost certainly disputes it. Assume both until we have checked.

HGH Fragment 176-191 reaches users through the gray-market peptide economy aimed at fat loss and body composition, sold alongside and as AOD-9604. There is no approved product, and its market persists despite the failed obesity trials.

How we got here

HGH Fragment 176-191 is the 16-amino-acid C-terminal region of human growth hormone (residues 176 to 191), identified at Monash University as the portion carrying the hormone's lipolytic activity without its growth-promoting or glucose-disrupting effects. This fragment served as the structural basis for AOD-9604, a tyrosine-modified analog. Both were marketed and studied for fat loss.

HGH Fragment 176-191 is the naturally occurring lipolytic tail of growth hormone that researchers tried to develop into a fat-loss drug. The optimized, stabilized version, AOD-9604, was taken into obesity trials at an Australian university and failed, after which the bare fragment continued to circulate in the gray market.

The numbers behind the grade

Type
HGH fragment
Region
176-191
Optimized form
AOD-9604
Obesity trials
Failed
Approved
No
Sport
Prohibited

The people taking it

The bare fat-burning fragment of growth hormone and the unrefined twin of AOD-9604, sharing that compound’s appealing concept and its failed human obesity trials.

Its users are fat-loss and body-composition seekers in the gray-market peptide community, often unaware of the failed clinical record.

The bare growth-hormone fragment sold gray-market for fat loss, interchangeable with AOD-9604, whose failed obesity trials define its evidence.

Set against the alternatives

HGH Fragment 176-191 is the unmodified twin of AOD-9604, and the two are best read together. Against the GHRH analogs like Mod GRF and Tesamorelin, which actually raise growth hormone, this fragment instead tries to isolate one downstream effect, fat mobilization, and unlike those it failed its human trials. Its identity is inseparable from AOD-9604’s disappointing clinical story.

What we do not know

  • Why a concept with clear preclinical logic failed in human trials.
  • Whether any subgroup or formulation could ever show benefit.
  • Why the gray market continues to sell it despite the failure.

The market for this

What follows describes how this is bought and sold. It is not a buying guide and it is not an endorsement of any seller.

HGH Fragment 176-191 is a gray-market fat-loss peptide that is essentially the unrefined form of AOD-9604, which failed its human obesity trials. Anyone considering it should read the AOD-9604 entry, recognize that the appealing concept did not pan out in people, and not expect meaningful fat loss from a compound whose optimized version could not beat placebo.

Gray-market research vials, with quality and even identity often unverified.

What this entry does not yet cover

What follows is unfinished work on our side, not a finding about HGH Fragment 176-191.

  • Timeline. We have not built the dated record of research and regulatory events.
  • Supply chain. We have not mapped where it is made.
  • What could change. No forward-looking summary yet.

Sources

The studies that matter

  • Lipolytic conceptpreclinical

    The 176-191 tail of growth hormone appears to carry its fat-mobilizing activity without the growth effects.

  • Clinical failurehuman

    The optimized version, AOD-9604, failed its obesity trials, with no meaningful fat loss over placebo.

  • Gray-market identitycurrent

    The bare fragment is sold almost interchangeably with AOD-9604 despite that failed clinical record.