AOD-9604

What it is

Growth hormone does 2 things that otherwise only come as a pair: it makes things grow, and it breaks down fat. Anyone who took it to lose weight would get the growth as well. It raises blood sugar, and it makes tissue grow that you do not want to grow. That is why growth hormone is not simply prescribed.

So researchers looked at the molecule and asked whether the two effects sit in different places. The fat-burning effect appeared to lie at the tail end of the protein. They cut off this end, 16 amino acids, and turned it into AOD-9604. The name stands for Anti-Obesity Drug.

How it is supposed to work

The fragment is supposed to trigger the fat-burning part of the growth hormone effect without bringing along the growth signals. That is exactly what was measured: no rise in IGF-1, that is, no growth signal, and no worsening of glucose utilization.

Half the idea worked. The growth was indeed cut off. What remained open was the other half, namely whether what is left helps with weight loss.

What was actually tested

An Australian company, Metabolic Pharmaceuticals, developed AOD-9604 over several years as a serious drug program. 6 randomized, double-blind, placebo-controlled trials were conducted, with around 900 overweight adults, with single and repeated administration, injected and swallowed, the longest over 24 weeks.

A medium-sized trial over 12 weeks initially looked useful: 2.6 kilograms of weight loss versus 0.8 kilograms on placebo. No miracle, but a signal. So the company moved on to the large trial with 534 participants over 24 weeks. There the primary endpoint was missed; there was no difference from placebo that counts. In 2007 development was discontinued, there was never a phase 3, and AOD-9604 has not received approval as a medicine in any country.

From failed drug to supplement

The molecule was still there, and it had a property that is worth money: a spotless safety profile. So it was repurposed. In the US it received the status Generally Recognized As Safe, that is, the classification for ingredients in dietary supplements.

That is legally sound, and the classification says exactly what it says on the label: it is a statement about safety. It says not a word about efficacy. Water is also generally recognized as safe.

The trick in the advertising

Sales pages say, in essence: clinically tested, excellent safety profile, studied in trials with hundreds of participants. Every single one of these words is true. They are the safety data, and they are presented as if they were efficacy data.

This is more sophisticated than the usual. For most substances the trick is simple, namely selling mouse data as human data. Here the trials, the participant numbers and the safety are all correct. All that is swapped is which question they answer.

What the studies show

The 12-week trial — the signal

According to company statements, a medium-sized trial over 12 weeks showed 2.6 kilograms of weight loss versus 0.8 kilograms on placebo. That was no miracle, but enough to push development further.

The large trial — 534 participants

Randomized, double-blind, placebo-controlled, 534 participants, 24 weeks. The primary endpoint was missed; there was no difference from placebo that counts. This is the usual pattern: a small trial looks good, a large trial says no. That is not bad luck but statistics, because in small groups everything fluctuates more, and what remains when you measure on a large enough scale is the truth.

The program as a whole

6 randomized, double-blind, placebo-controlled trials, around 900 overweight adults, single and repeated administration, injected and swallowed, up to 24 weeks. That is more testing than the vast majority of substances in this field have ever seen. In 2007 development was discontinued; there was never a phase 3.

What the studies do not support

What is not supported is the benefit — and doubly so. First, the program itself did not show it: 534 people, 24 weeks, no effect on the primary endpoint. Second, even this negative finding is only a company statement, because the trial was never published. For most peptides the testing is missing. Here it apparently took place, but outsiders cannot inspect it.

The early positive pilot study does not carry this. It is precisely this study that sales pages cite almost exclusively, while the failed larger program goes unmentioned. And the American classification as generally safe is not proof of efficacy but a statement about safety. A well-conducted safety study is sometimes even the opposite of proof of efficacy, namely what remains when efficacy has failed to show.

Status, approval and legal

AOD-9604 has not received approval as a medicine in any country, and a phase 3 was never started. In the US the substance has the status Generally Recognized As Safe for dietary supplements, which is purely a statement about safety. On the FDA list of substances with possible safety risks in pharmacy compounding, AOD-9604 appears among the withdrawn nominations; there the FDA cites a possible risk of an immune reaction. For athletes: AOD-9604 is on the prohibited list of the World Anti-Doping Agency, there is a reliable urine test, and anyone who competes in organized sport, including licensed amateur sport, risks a ban.

Safety

The safety profile is unusually well studied for this field and was indistinguishable from placebo in the trials: no serious side effects, no rise in IGF-1, no antibody formation, no worsening of glucose utilization, and none of the side effects known from full growth hormone. This applies to the tested uses up to 24 weeks and to trial preparations. No data are available for longer periods, and these data do not apply to gray-market products anyway.

Sources

• Metabolic Pharmaceuticals, AOD-9604 development program (6 randomized, double-blind, placebo-controlled trials, around 900 adults)
• Medium-sized trial over 12 weeks, 2.6 versus 0.8 kilograms
• Large trial with 534 participants over 24 weeks, primary endpoint missed (2007)
• Stier H, Vos E, Kenley D, J Endocrinol Metab 2013 – safety of AOD9604 in 6 randomized trials (pooled analysis)
• FDA – substances with possible safety risks in pharmacy compounding (as of April 2026)
• Generally Recognized As Safe, classification in the US
• WADA, Prohibited List (prohibited list of the World Anti-Doping Agency)