AOD-9604 is a synthetic 16-amino acid fragment of human growth hormone engineered to trigger fat breakdown without the growth-promoting or blood-sugar-disrupting effects of full-length GH.
What it does
AOD-9604 is taken from the C-terminal end of human growth hormone (amino acids 176–191) — the region responsible for GH's fat-burning activity. It activates β3-adrenergic receptors on adipocytes (fat cells), which kicks off a signaling chain: adenylyl cyclase raises intracellular cAMP, which activates hormone-sensitive lipase (HSL), the enzyme that breaks triglycerides apart into free fatty acids and glycerol that the body can burn for energy al. 2001 al. 2000. Separately, it inhibits acetyl-CoA carboxylase and fatty acid synthase — two enzymes required for de novo lipogenesis (the liver and fat cells building new fat from scratch) — reducing how much new fat gets stored al. 2001 PubMed 11673763.
The key distinction from full-length GH: AOD-9604 does not activate the IGF-1 receptor. Full-length GH drives IGF-1 production, which has anabolic (tissue-building) and mitogenic (cell-proliferation) effects and can raise blood sugar. AOD-9604 isolates the lipolytic signal and discards the rest al. 2000 PubMed 15134286. That selectivity is also why the Australian TGA granted it GRAS (Generally Recognized As Safe) status for use in oral food and supplement formulations — a regulatory milestone no other GH-derived peptide has reached PubMed 16625817.
What the evidence shows
Fat loss and obesity treatment Strong rodent evidence; multiple phase I–II human trials with modest effect sizes; no phase III success to date
In obese mice, chronic AOD-9604 treatment increased fat oxidation and produced significant weight loss comparable in magnitude to full-length GH — without elevating IGF-1 or impairing glucose tolerance PubMed 11673763 al. 2001. Human trials moved through phase I and into phase II/III under the brand name Metabolin. Phase II results showed modest but measurable reductions in body fat at 1 mg/day oral dosing PubMed 15134286 PubMed 14685303 PubMed 14571286. However, the phase III trial did not meet its primary endpoints for meaningful weight loss, and the obesity drug program was discontinued PubMed 22435392 PubMed 17971763. Reviews of obesity pharmacology cite AOD-9604 as a notable mechanistic approach that failed to translate into clinically significant outcomes at oral doses tested PubMed 16931496 PubMed 16625817 PubMed 15834452.
Osteoarthritis and cartilage repair Early-stage; one published rabbit model; human data limited to self-reports and one small trial context
A rabbit osteoarthritis model found that intra-articular injection of AOD-9604, with or without hyaluronic acid, reduced cartilage degradation markers compared to controls PubMed 26275694. The mechanism is not fully characterized but may involve AOD-9604's influence on lipid metabolism in joint tissue or direct effects on chondrocytes (cartilage cells). Reviews of peptide therapy in orthopaedics list it as an emerging candidate PubMed 41490200 PubMed 41966639, but human clinical data on this application is essentially absent.
Athletic performance / body composition Mostly anecdotal in humans; flagged by anti-doping authorities
AOD-9604 appears regularly in anti-doping literature because athletes self-administer it subcutaneously for body composition PubMed 26213263 PubMed 25382550 PubMed 24906629. Detection methods for AOD-9604 in urine have been developed and validated PubMed 25208511 PubMed 26578461, and seized pharmaceutical preparations have been analyzed and confirmed PubMed 24976118. Notably, AOD-9604 does not interfere with the WADA hGH isoform immunoassay — meaning it won't trigger a false positive for GH doping — though it remains a prohibited substance PubMed 24124033. No controlled human trials on performance or body composition exist.
How it's used
In studies and self-reported protocols, subcutaneous doses range from 250 mcg/day (low) to 500 mcg/day (moderate) to 1,000 mcg/day (high), typically injected in the morning in a fasted state. The half-life is approximately 30 minutes, so once-daily morning dosing is the standard approach. The human obesity trials used oral dosing (1 mg/day), but the bioavailability of oral AOD-9604 appears lower than subcutaneous, and the two routes are not directly interchangeable in self-reported use. Injection site reactions are the most commonly noted tolerability issue with subcutaneous administration.
Side effects and safety
Reported side effects are mild: injection site reactions, occasional headache, and GI complaints (nausea, indigestion) at higher doses. No severe adverse events have been documented in published trials. Because AOD-9604 does not raise IGF-1 or activate the GH receptor, the risks associated with full GH therapy — glucose intolerance, acromegaly (abnormal bone and tissue growth), fluid retention — are not expected and have not been observed al. 2000 PubMed 15134286. The TGA's GRAS designation for oral use supports a reasonable short-term safety profile at studied doses. What remains unknown: long-term safety data beyond the trial windows studied, effects in people with hepatic impairment (a listed relative contraindication), and safety in populations not studied (pregnant women, adolescents). Anti-doping seizures confirm it is used in non-clinical contexts, but self-reported safety data from those populations is not systematically collected.
Bottom line
AOD-9604 has a well-defined mechanism and solid rodent data, but its phase III failure for obesity means the clinical proof of concept in humans is incomplete. The safety profile looks clean relative to full-length GH, which is genuinely meaningful, but that advantage matters less if the efficacy signal is weak. It may be of interest to people researching GH fragment pharmacology or early-stage joint repair approaches, but anyone expecting dramatic fat loss based on rodent data alone should temper expectations.