Digestive & weight GH C-terminal fragment
Fragment 176-191
Regulatory status
Status at a glance
503A compounding status
Not nominated
We found no pending nomination for the 503A bulks list. Unless the substance has another legal pathway (for example, a USP monograph or use in an FDA-approved drug), 503A pharmacies generally may not compound with it.
- FDA approval
- Not FDA-approved for any use
- 503B outsourcing
- Not determined
- Anti-doping (WADA)
- On the WADA Prohibited List
- DEA schedule
- Not a controlled substance
About peptide status
Most peptides discussed here are not FDA-approved for any use, and products labeled “research use only” are not for human use. Removal from Category 2 does not authorize compounding. PCAC votes are non-binding recommendations; FDA and HHS make the final decisions.
This is not medical or legal advice, and we do not publish dosing, sourcing or reconstitution information. Talk with a licensed clinician before using any peptide.
If you think you are having a medical emergency, call 911.
Key takeaway
Fragment 176-191 is the unmodified tail piece of human growth hormone, sold on the wellness market as a fat-loss "research peptide." Its evidence is limited to animal and laboratory work. In rat fat-pad experiments, a close relative (hGH 177-191) matched whole growth hormone's antilipogenic activity but showed no significant lipolytic effect (Wu and Ng, 1993). Its modified cousin, AOD-9604, failed in human obesity trials. As of 2026 the fragment is not FDA-approved and is banned in sport.
At a glance
- FDA status
- Non-FDA-approved peptide sold in the wellness/gray market
- What it is
- C-terminal fragment of the growth hormone molecule, marketed for fat loss
- Research
- Evidence is animal and laboratory only; its optimized cousin AOD-9604 failed human trials
- Sport
- Prohibited by WADA at all times
- Evidence strength
- Low research
Summary
Fragment 176-191 is a growth hormone fragment sold for fat loss. Learn how it is proposed to work, its non-approved status, and what the research shows.
What is Fragment 176-191?
Fragment 176-191 is the C-terminal (tail) fragment of human growth hormone, sold on the "research peptide" market for fat loss. It is closely related to AOD-9604, which is this fragment with an added stabilizing amino acid; the two are often conflated and sold interchangeably, but AOD-9604 is the engineered, better-studied version. Much of what vendors label "176-191" is pharmacologically the same fat-metabolism concept.
How does it work?
The proposed theory is that the fat-related activity of growth hormone is concentrated in this tail fragment, so the fragment alone might reduce fat storage without the hormone's growth or glucose effects. In rat studies, the fragment was shown to carry the anti-fat-storage activity of the parent hormone, localizing that function to the C-terminal region. The tested peptide was hGH 177-191, a close relative of this fragment, and it showed no significant lipolytic effect in rat fat pads. These are animal and cell findings. This describes the proposed mechanism, separate from proven outcomes.
The more detailed mechanism data belong to AOD-9604, the modified version, and not to the bare fragment. In obese Zucker rats, AOD-9604 cut weight gain over 50% in 19 days and raised lipolytic activity in adipose tissue, without the insulin-sensitivity harm seen with intact growth hormone. In obese mice, AOD-9604 increased fat oxidation and plasma glycerol, a marker of fat breakdown, and it did not compete for the growth hormone receptor or drive cell proliferation.
Is it FDA-approved?
Safety note
Status: Non-FDA-approved peptide sold in the wellness/gray market
Category: Wellness and performance · Primary body area: Digestive & weight
No. Fragment 176-191 is not approved by the FDA; it is a "research chemical" with no approved drug or recognized compounding status, sold through gray-market channels. AOD-9604, the modified version, was developed by Metabolic Pharmaceuticals as an obesity drug, but its development was terminated in 2007 after it failed to show efficacy. In sport, growth hormone fragments including "hGH 176-191" are prohibited at all times under the WADA list.
What does the research show?
Editor’s note
Evidence strength: Low research (2 human · 0 animal/cell studies)
The fat-metabolism rationale is supported only by animal and laboratory work, there is no human efficacy evidence for the fragment itself, and its optimized cousin failed in human trials.
The evidence is preclinical. Animal work localized the anti-lipogenic activity of growth hormone to this C-terminal fragment, and the closest human data belong to its modified version, AOD-9604, whose obesity trials failed to beat placebo. There are no controlled human trials of the bare fragment for fat loss, so its marketed benefit is unproven.
The human data belong to AOD-9604, as reported in a review of obesity drug development.
| AOD-9604 trial | Result |
|---|---|
| 12-week trial | AOD-9604 recipients lost 2.6 kg against 0.8 kg on placebo |
| 24-week trial of 536 people | Failed to produce significant weight loss, which ended the obesity program |
Those results do not describe the bare fragment, which has not been tested in controlled human trials.
Sources: animal research localizing the growth hormone fragment's fat activity (Wu and Ng, Biochemistry and Molecular Biology International, 1993, PubMed PMID 8358331) and animal fat-metabolism studies of the related AOD-9604 (Ng et al., Hormone Research, 2000, DOI: 10.1159/000053183), indexed on PubMed; and the WADA Prohibited List. This document is educational, is not medical advice or a health claim, and is not an offer to sell any product.
Registered human trials
2 registered human trials on ClinicalTrials.gov that we reviewed
Sources
- [1]
- PMID 8358331
- [2]
- [3]
- [4]
- [5]
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