AOD-9604

AOD-9604 is a lab-made peptide (a small chain of protein building blocks) that was once developed as an anti-obesity drug. Today it’s sold widely as a “fat-loss peptide” — but the human studies behind it were small, short, and ended in disappointment.

What it is

AOD-9604 stands for “Anti-Obesity Drug 9604.” It’s a synthetic piece of human growth hormone (hGH) — specifically the tail end of the molecule (amino acids 176-191), with one extra building block (a tyrosine) added to help it hold together. The thinking, worked out at Monash University and Metabolic Pharmaceuticals in Australia back in the 1990s, was simple: take just the fat-burning part of growth hormone and leave the rest of its body-wide effects behind. In the company’s own studies, it didn’t seem to raise IGF-1 (a growth-signaling hormone) or switch on the growth hormone receptor the way the full hormone does.

The claims

Marketing pitches AOD-9604 as a peptide that kick-starts fat breakdown (lipolysis) and blocks the body from storing new fat (lipogenesis) — all without touching appetite, blood sugar, or growth-hormone pathways. Sellers and clinics often call it a clinically studied, “GRAS-approved” fat-loss aid. But as we’ll explain below, “GRAS” is just a narrow food-ingredient label. It isn’t drug approval, and it’s not proof that the stuff actually works for fat loss.

What the evidence actually shows

The basic biology has real support in the lab. Studies in rodents and in cells (for example, Heffernan and colleagues in Endocrinology, 2001) found that both hGH and AOD-9604 lowered body weight and fat mass. Interestingly, that fat-burning effect seemed to work mostly without relying on the beta-3 adrenergic receptor (one of the body’s usual fat-burning switches), so exactly how it works in people is still unclear.

The human side is much weaker than the ads suggest. AOD-9604 went through a string of placebo-controlled trials in adults with obesity (where some people get the real drug and some get a dummy, so you can compare). An early 12-week study reported modest weight loss on a 1 mg/day dose taken by mouth (roughly 2.6 kg versus about 0.8 kg on placebo). But the big, make-or-break Phase IIb trial — the one that really counted toward approval, with several hundred participants — did not beat placebo by a meaningful margin (one large enough to rule out chance). Metabolic Pharmaceuticals stopped developing AOD-9604 for obesity in 2007. So the short version is: promising biology, a small early hint of benefit, and then a clear failure in the very trial built to prove it worked. Claims about joints, cartilage, or anti-aging rest on even thinner evidence.

Legal and regulatory status

As of June 2026, AOD-9604 is not an approved drug anywhere — not with the FDA (U.S.), the EMA (Europe), or Australia’s TGA. It did get a GRAS (Generally Recognized as Safe) notice for use as a food ingredient, but that’s a narrow food-additive lane. It is not drug approval, and it says nothing about whether it works for fat loss.

For compounding pharmacies (pharmacies that mix custom medications), the situation recently got tighter. At its December 4, 2024 meeting, the FDA’s Pharmacy Compounding Advisory Committee reviewed AOD-9604 (in both its free base and acetate forms), and the FDA proposed against adding it to the 503A bulks list (the approved list of ingredients pharmacies can compound from), pointing to limited safety information and worries about immunogenicity (the risk of triggering an immune reaction) and peptide-related impurities. In plain terms, that means it isn’t a legitimately compoundable drug in the U.S. And in sports, the World Anti-Doping Agency bans AOD-9604 at all times under category S2 (peptide hormones, growth factors, and related substances and mimetics).

Safety

Across the company’s controlled trials, AOD-9604 was generally reported as well tolerated over a few months, without the IGF-1 jumps or blood-sugar problems you see with full growth hormone. That’s reassuring, but it only goes so far: the trials were short, much of the dosing studied was taken by mouth rather than the injections sold today, and there are no long-term human safety data. The FDA specifically flagged the risks of immunogenicity (immune reactions) and product impurities. Anything sold online is unregulated and may differ in purity and dose from whatever was actually tested. None of this is medical advice.

Bottom line

AOD-9604 has a believable way of working and a real — if modest — early hint in humans. But the trial built to confirm a fat-loss benefit failed, the company walked away from it, and it remains unapproved as a drug everywhere. The best way to think about it: a shelved drug candidate now being sold ahead of its evidence.

Evidence grade: 7/10 · Moderate.

Sources

• Heffernan M, et al. The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism following chronic treatment in obese mice and beta(3)-AR knock-out mice. Endocrinology, 2001.
• The effect of AOD9604 on weight loss in obese adults: results of a randomized, double-blind, placebo-controlled, multicenter study (Diabetes, Obesity & Metabolism).
• FDA, December 4, 2024 Meeting of the Pharmacy Compounding Advisory Committee.
• WADA, The Prohibited List (S2: Peptide Hormones, Growth Factors, Related Substances and Mimetics).