AOD-9604

AOD-9604, sometimes written AOD9604, is a synthetic peptide corresponding to the C-terminal lipolytic fragment of human growth hormone, spanning amino acids 176 to 191 with an additional tyrosine residue added at the N-terminus ^[5]. Human growth hormone has long been known to stimulate fat breakdown, and researchers led by Frank Ng at Monash University in Australia set out to isolate just the fat-reducing portion of the molecule, producing this short peptide, a so-called Anti-Obesity Drug fragment, in the late 1990s and early 2000s ^[3].

The premise was to capture growth hormone's lipolytic and fat-oxidizing effects while avoiding its unwanted actions on blood sugar and tissue growth. In obese rodents, chronic treatment with AOD-9604 reduced body weight gain and body fat, raised fat oxidation, and increased expression of the beta-3 adrenergic receptor that drives lipolysis in fat cells, without the hyperglycemia or insulin resistance produced by intact growth hormone ^[1][2][3]. Importantly, the peptide does not bind or compete at the growth hormone receptor and does not stimulate cell proliferation, distinguishing it mechanistically from growth hormone itself ^[1].

AOD-9604 was developed by Metabolic Pharmaceuticals as an oral anti-obesity candidate and progressed into human clinical evaluation ^[4], but it did not gain approval as a weight-loss drug, and its human efficacy proved far more modest than the animal data suggested. It has since been marketed as a research peptide and in some markets promoted for fat loss, joint, and recovery uses; it is banned in sport by the World Anti-Doping Agency and is detectable in anti-doping tests ^[5]. It is typically supplied as a lyophilized powder for reconstitution.

AOD-9604 is a synthetic fragment of human growth hormone (residues 176-191) marketed for fat loss; human safety data are limited, and although trials suggested general tolerability it was not approved as a weight-loss drug. Reported effects are generally mild and include injection-site reactions, but its long-term safety and drug interactions are not established, and it is sold as a research chemical.

AOD-9604 was developed during the 1990s by researchers at Monash University in Melbourne, Australia, in collaboration with the biotechnology company Metabolic Pharmaceuticals. It was engineered from the C-terminal region of human growth hormone (residues 176-191), the segment shown to carry growth hormone's fat-reducing activity, with a tyrosine residue added to improve stability. The peptide advanced into human clinical testing as a candidate anti-obesity drug in the 2000s, but the weight-loss effect in trials proved modest and it was not approved for that indication. It has since been repurposed as a research peptide and explored for additional applications, including cartilage and joint health.

AOD-9604 is valued for a distinctive premise among fat-loss peptides; in animal studies it reproduced growth hormone's lipolytic, fat-burning effects while sparing insulin sensitivity and avoiding the tissue-growth signaling of full growth hormone. That clean separation of benefit from growth hormone's metabolic drawbacks is what draws interest from those seeking body-composition support. In animal testing it has shown a favorable tolerability profile and is generally regarded as well tolerated. In the interest of honesty, the strongest results are largely preclinical and human weight-loss data have been limited, so it is best viewed as promising rather than proven.