HGH Fragment 176-191 (AOD-9604) — What the Evidence Actually Shows

What it is

HGH Fragment 176-191 is a piece of the growth-hormone molecule marketed as a targeted fat-loss peptide. It was actually developed as a drug candidate (AOD-9604), which means — unlike most compounds here — it has real human trial data. That data is the reason it sits in the “marketing claim” tier.

Composition

It corresponds to amino acids 176–191 — the tail end — of the human growth-hormone molecule. The idea was to isolate the part thought to drive fat metabolism while leaving out growth hormone’s other actions (including its effects on growth and blood sugar).

Proposed mechanism

It is proposed to stimulate fat breakdown (lipolysis) and inhibit fat formation, mimicking growth hormone’s effect on fat tissue without raising IGF-1 or blood glucose.

Claimed benefits

Targeted fat loss without the side effects of growth hormone — a very heavily promoted “fat-burning peptide” pitch.

What the evidence shows

Marketing claim· human data. This is the clearest claimed-vs-shown case in this section. As the drug candidate AOD-9604, the fragment went through multiple human trials — and its largest Phase IIb obesity trial failed to show a significant benefit, after which development was discontinued in 2007. The compound was generally tolerated, but “tolerated” is not “effective.” The strong fat-loss marketing is not supported by the human evidence that actually exists.

Legal & regulatory status

Never approved as a weight-loss medicine — development was abandoned. Sold as a research chemical. As an unapproved growth-hormone-related peptide it should be treated as prohibited in sport under the WADA code.

Known risks & unknowns

Trials reported reasonable short-term tolerability, but there is no approved product, no long-term safety data for this use, and research-chemical versions carry purity and dosing unknowns. The bigger “risk” for most buyers is simpler: paying for an effect the pivotal human trial didn’t deliver.

Sources

Frequently asked questions

Does HGH Fragment 176-191 burn fat?

This is the clearest 'marketing claim vs evidence' case in this section. The fragment (developed as the drug candidate AOD-9604) went through multiple human trials — and its largest Phase IIb obesity trial failed to show a significant benefit, after which development was stopped in 2007. The strong fat-loss marketing is not backed by that human evidence.

What is it, chemically?

It is a short fragment corresponding to the tail end (amino acids 176–191) of the human growth-hormone molecule, designed to mimic GH's fat-metabolism effects without its other actions. In practice, the hoped-for fat-loss effect did not hold up in the pivotal human trial.

Is it safe?

The trials generally reported it was tolerated, but 'tolerated' is not the same as 'effective', and unregulated 'research chemical' versions carry the usual purity and contamination unknowns. It has no approval for weight loss.

Is it banned in sport?

As an unapproved growth-hormone-related peptide it falls under the WADA prohibited categories and should be treated as banned in sport.

Related compounds

Tesamorelin — Well-supported

An evidence-tiered, non-promotional explainer on tesamorelin (Egrifta): a GHRH analogue, the one GH-releasing peptide with FDA approval and robust trial data — for a specific medical use, not fitness.

MK-677 (Ibutamoren) — Preliminary

An evidence-tiered explainer on MK-677 (ibutamoren): an oral ghrelin-receptor agonist — technically not a peptide — that raises GH and IGF-1, with real but modest human trial data and no approval.

GLP-1 receptor agonists — Well-supported

How GLP-1 receptor agonists (semaglutide, tirzepatide) differ from the unregulated 'research peptides': real large-scale trials, regulatory approval, and prescription-only status.