AOD-9604 (hGH fragment 176-191 analog)
AOD-9604 — the fat-loss peptide that failed its human trial: the honest evidence

Class: peptide
Synonyms: AOD-9604
"Anti-Obesity Drug 9604"
CJC-tyrosine-fragment. INCI: none
Function tags: (intended:) fat loss / lipolysis
(failed:) obesity/weight-loss drug
(gray-market:) joint/recovery
Overall evidence grade: B
WADA prohibited: yes
WADA note: Sport WADA-prohibited: growth-hormone fragments including AOD-9604 / hGH 176-191 are on the banned list. Detectable; sanctionable regardless of intent.
Last updated: 2026-07-13

In brief: AOD-9604 is a synthetic fragment of growth hormone's fat-burning tail (residues 176-191, stabilised with a tyrosine and a disulfide bridge), engineered by Metabolic Pharmaceuticals in the 1990s to isolate GH's lipolytic effect without its growth/IGF-1/glucose effects. On the design goal it succeeded — it doesn't raise IGF-1 or disturb blood sugar, and its safety across six trials in 900+ people was reassuring. But on the thing that matters, it failed: a pivotal Phase 2b trial in 500+ obese adults missed its primary weight-loss endpoint, the effect was too small to be clinically meaningful, and Metabolic Pharmaceuticals abandoned it in 2007. This is the register's clearest example of an honest debunk — not "unproven because nobody studied it," but "studied properly and it didn't work." It's still sold everywhere for fat loss; the single most useful fact a reference can carry is that it flunked its own pivotal trial. It's also not FDA-approved, FDA-flagged as a risk-bearing bulk substance, and WADA-banned in sport.

## Identity a synthetic **16-amino-acid peptide** based on the **C-terminal region of human growth hormone** (residues ~176/177-191) with two engineering tweaks: a **tyrosine added at the N-terminus** and a **disulfide bridge** (cyclisation) that makes it far more **resistant to enzymatic breakdown** in plasma (better stability/bioavailability than the raw fragment). The design hypothesis: **isolate GH's fat-burning (lipolytic) action** while leaving out its growth-promoting, IGF-1-raising and diabetogenic effects. ## Mechanism (as proposed) AOD-9604 corresponds to the **C-terminal lipolytic domain of hGH**. In preclinical models it **stimulates lipolysis (fat breakdown) and inhibits lipogenesis (new fat formation)** — but, crucially, it **does not bind/activate the classical growth-hormone receptor**, so it produces these fat effects **without** the IGF-1 rise, insulin resistance, or tissue-growth signals of full-length GH. Mechanistically that's an appealing "clean lipolysis" story — and it's **real in animals**. The problem is purely translational: the isolated lipolytic effect, genuine in the lab, **simply wasn't powerful enough to drive meaningful weight loss in humans** at the doses tested. Elegant mechanism, clean safety, **negative pivotal trial.**

Evidence grades by outcome:
outcome: Weight loss / obesity (the intended use)
grade: F
base: Pivotal Phase 2b (~500+ obese adults, 12 wk, placebo-controlled): did NOT meet primary endpoint; effect modest, not clinically meaningful → development abandoned 2007
caveat: The strongest kind of "F" — tested in a proper trial and failed. Not a data gap; a negative result
outcome: Lipolysis / fat metabolism (mechanistic)
grade: D
base: Animal + in-vitro: stimulates fat breakdown, inhibits lipogenesis (receptor-independent)
caveat: Real in the lab / animals — but the lab effect did not translate into human weight loss (that's the whole lesson)
outcome: IGF-1 / glucose neutrality (the design goal)
grade: B
base: Human trials: no IGF-1 elevation, no glucose disturbance
caveat: Here the molecule genuinely delivered — it is metabolically clean; unfortunately "clean but ineffective" doesn't make a drug
outcome: Joint / osteoarthritis (repurposing)
grade: F
base: Explored post-obesity; some interest
caveat: Not established; a second unproven indication
outcome: Safety / tolerability
base: 6 trials, 900+ participants
caveat: Well-characterised, well-tolerated (this is genuinely its strong suit) — but safety without efficacy isn't a therapy; and it's FDA-flagged as a bulk substance + WADA-banned

Legal status:
region: US
status: Not approved
note: not FDA-approved for any use; listed by the FDA as a bulk drug substance that may present safety risks (i.e. flagged, not endorsed).
region: EU
status: Not FDA-approved (gray-market)
note: not approved; investigational/research chemical; not a cosmetic.

Cosmetic claims:

Note: The register's cleanest honest-debunk: a fat-loss peptide that was properly tested in humans — and failed. Three points define this entry: (1) unlike most gray-market compounds (F because untested), AOD-9604 is F because it was tested and didn't work — it ran six human trials in 900+ people and missed its primary weight-loss endpoint in a pivotal Phase 2b; (2) its safety was actually good (no IGF-1/glucose problems) — the failure was efficacy, which is the more damning kind; (3) it's still sold everywhere for fat loss, making the honest "it flunked its own pivotal trial" the single most useful thing a reference can say.
Status note: status stable — a failed/abandoned obesity program; unlikely to change absent a new indication with real data

Sources:
Ng FM, Heffernan M, et al. — C-terminal hGH fragment lipolysis work (Monash / Metabolic Pharmaceuticals); Effects of a synthetic hGH fragment on lipid metabolism. Am J Physiol Endocrinol Metab. 2000 (PMID 10950816).
Phase 2b obesity trial (Metabolic Pharmaceuticals, ~500+ adults) — primary endpoint not met; development discontinued ~2007 (reported across the clinical-review literature).
FDA — AOD-9604 listed among bulk drug substances flagged for potential safety risks (not compoundable/approved).
WADA 2026 Prohibited List — growth-hormone fragments incl. AOD-9604 / hGH 176-191.
Safety database: six controlled trials, 900+ participants (well-tolerated; no IGF-1/glucose signal).