Peptide Graded

All peptides / Gut and weight

Fragment 176-191

GH C-terminal fragment

Also HGH Fragment 176-191, hGH Frag 176-191, Frag 176-191, GH Fragment 176-191, HGH Frag, AOD-9604

Evidence
CAnimal and cell studies
FDA status
Not approvedas of 2026-10-26
Route
Injection
Studies cited
0 human3 animal or cell

It is sold as a fat burner made from part of growth hormone. It shrank fat in rats, but the human weight-loss trials of the same molecule failed.

Sold for

Fragment 176-191 is sold as the fat-burning piece of growth hormone, with none of growth hormone's effects on blood sugar or growth.

Studies say

Rodent studies support a fat-mobilizing effect, and the human obesity trials run under the name AOD9604 failed, which puts it at C.

Why grade C. The published evidence for fat loss is three rodent studies showing reduced weight gain and increased fat breakdown in obese rats and mice. 123 Human trials of the identical compound (AOD9604) were run by its developer in the 2000s, with the largest reported at about 500 participants, but they did not meet their weight-loss endpoints and were never published, so for the claimed use there is no positive human evidence. 4

FDA. Not approved by the FDA for any use and sold as a research chemical. The same molecule was developed as AOD9604 by an Australian company, which stopped the program after phase 2 obesity trials failed to show weight loss; no application was ever filed. 4

Written from 5 cited sources. Last refreshed 2026-10-27. Not physician reviewed.

What this means for you

What people take it for
Burning body fat
Can a US doctor prescribe it?
No. It is not approved and is sold as a research chemical.
Properly tested in people?
Not properly: animal or lab studies, or small uncontrolled human reports. Human trials of about 500 people did not show weight loss.

Evidence checklist

  • Randomised controlled trial Rodent studies only; human trials unpublishedno
  • Human study over 100 people No published human studyno
  • More than one research group Developer's human trials failed, unpublishedno
  • Clinical outcomes, not surrogate markers No positive human outcomeno
  • Human safety data beyond case reports Only the developer's reports; no repeated-use datano

Drawn from the cited studies below. A dash means the sources give no information.

What it is

Fragment 176-191 is a lab-made peptide. It copies the last sixteen amino acids of the human growth hormone molecule, which has 191 amino acids. Research in the early 1990s suggested that this C-terminal tail drives growth hormone's effects on fat metabolism. A 1993 study showed that a synthetic fragment (177-191) reduced fat synthesis in rats. It did not stimulate fat breakdown. 1

Metabolic Pharmaceuticals in Melbourne developed a stabilized version with an added tyrosine. It is called AOD9604, and it was meant as an oral obesity drug. Research-chemical suppliers make the product sold online as 'fragment 176-191' or 'HGH frag'. It is this compound or its unmodified parent. It is not a growth hormone secretagogue. It does not raise growth hormone levels. 24

How it works

The proposed mechanism is that the fragment mimics the lipolytic (fat-releasing) action of growth hormone. It does this without binding the growth hormone receptor. In obese mice the fragment increased fat oxidation and plasma glycerol, a marker of fat breakdown. It also reduced weight gain. Yet it did not compete with growth hormone for its receptor. It did not stimulate cell proliferation. The authors suggested it works through the beta-3 adrenergic receptor on fat cells. That pathway is prominent in rodents and much less active in adult humans. 3

What human research shows

No peer-reviewed human trial of fragment 176-191 or AOD9604 for fat loss has been published. Metabolic Pharmaceuticals ran phase 2 trials of oral AOD9604 in obese adults in the mid-2000s. One lasted six months and had several hundred participants. In 2007 the company announced that the drug had not produced significant weight loss compared with placebo. It abandoned development for obesity. Reviews of obesity drugs list it among the discontinued candidates. 4

StudyModelFinding
Antilipogenic fragment 1993Rats, epididymal fat padsThe synthetic 177-191 fragment reproduced growth hormone's suppression of fat synthesis without a lipolytic effect. 1
AOD9604 in obese Zucker ratsRats, obese Zucker strain, 19 days oral treatmentWeight gain fell by more than half versus controls with increased fat-tissue lipolysis and no loss of insulin sensitivity. 2
AOD9604 in obese miceMice, ob/ob obese and lean, 14 daysReduced weight gain, increased fat oxidation and plasma glycerol, with no binding to the growth hormone receptor and no effect on blood glucose. 3
Obesity drug pipeline review 2013Review of discontinued and investigational obesity drugsAOD9604 is listed among candidates whose development stopped after clinical trials. 4

Safety

The developer's trials reportedly found AOD9604 well tolerated. In rodents it did not cause the insulin resistance or raised blood sugar that intact growth hormone does. That is all the safety data there is. Nobody has tested the injectable products sold online for purity. There are no data on repeated injections under the skin in people. 234

Questions for your clinician

  • Is there any published human trial showing fat loss from this compound?
  • What does it mean that the developer's obesity trials did not meet their goals?
  • How would I know what is in a vial sold online?

Questions people ask

Is fragment 176-191 FDA-approved?

No. Under the name AOD9604 it went through phase 2 obesity trials in Australia, which failed. No one ever submitted it to any regulator for approval. 4

Does fragment 176-191 burn fat in humans?

The developer's own placebo-controlled trials did not show significant weight loss. They involved several hundred obese adults. The program was dropped in 2007. The positive data come from rats and mice. 234

Does it raise growth hormone or IGF-1?

No. It is a piece of the growth hormone molecule, not a releasing agent. In mice it did not bind the growth hormone receptor. It is unrelated to secretagogues like ipamorelin or CJC-1295. 3

Is it the same as AOD9604?

AOD9604 is fragment 176-191 with an extra tyrosine at one end for stability. Online vendors use the names interchangeably. The human trial history belongs to AOD9604. 24

Citations

  1. Wu and Ng 1993, Biochemistry and Molecular Biology International: antilipogenic action of synthetic C-terminal sequence 177-191 of human growth hormone pubmed.ncbi.nlm.nih.gov
  2. Ng 2000, Hormone Research: metabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone pubmed.ncbi.nlm.nih.gov
  3. Heffernan 2001, International Journal of Obesity: increase of fat oxidation and weight loss in obese mice with growth hormone or a modified C-terminal fragment pubmed.ncbi.nlm.nih.gov
  4. Kakkar and Dahiya 2013, Current Cardiology Reviews: obesity pharmacotherapy, current perspectives and future directions pubmed.ncbi.nlm.nih.gov
  5. Ng 2000, Hormone Research: metabolic studies of AOD9604 (DOI record) doi.org

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