AOD-9604 is the lipolytic growth-hormone fragment engineered to act on fat cells without raising IGF-1.

The short version

AOD-9604 is a small lab-made peptide — a 16-amino-acid piece copied from the tail end of human growth hormone (hGH). Scientists at Monash University noticed that this one stretch of the hormone, around residues 176–191, seemed to handle the hormone's fat-burning work. So they rebuilt just that piece, hoping to get the fat effect on its own. The idea is elegant: in fat cells, AOD-9604 nudges them to break down stored fat (lipolysis) and make less new fat (it is antilipogenic), but it does not plug into the growth-hormone receptor and does not raise IGF-1 (the growth signal that comes with full hGH). Here is the honest catch: most of the proof is in mice and test tubes. When it was tested in people for weight loss, it did not beat placebo, and the obesity program was shelved. It is investigational — not an approved drug, not a supplement. What people report, including the let-downs, is on the effects page.

What AOD-9604 was built to do

AOD-9604 (also written AOD9604, AOD 9604, or HGH frag 176-191) is a synthetic hexadecapeptide — a chain of sixteen amino acids. Its sequence (YLRIVQCRSVEGSCGF) is modeled on the C-terminal end of human growth hormone, residues 177–191, with a tyrosine added at the front and an internal disulfide bridge that copies the loop of the parent hormone ^[3]. Its molecular weight is 1815.1 Da and its registry number is CAS 221231-10-3.

The design goal was specific: reproduce growth hormone's effect on fat metabolism while leaving out everything else. Full hGH builds tissue, raises IGF-1, and can push the body toward insulin resistance. AOD-9604 was engineered to skip that arm entirely — it does not bind the growth hormone receptor ^[3]. In adipocytes (fat cells), the parent C-terminal sequence interacts with the cell membrane, releases a second messenger, and inhibits acetyl-CoA carboxylase (ACC) — a key enzyme for building new fat — so the cell makes less of it ^[4]. This is the lipolysis-mechanism lens this site is built around, and it is where the most reproducible data lives.

The rodent data is real — the human result is the honest headline

In obese mice, fourteen days of chronic treatment reduced body weight and fat and raised beta-3 adrenergic receptor (beta3-AR) RNA in fat tissue — and the chronic weight effect needed working beta3-AR signaling to happen at all ^[1]. A companion study found increased fat oxidation and weight loss with the same C-terminal fragment ^[2]. Across the mouse work, the direction is consistent and the mechanism is traceable.

Then it reached people. Across roughly six placebo-controlled trials totaling about 900 obese adults, oral AOD-9604 was as safe and well-tolerated as placebo — and the pivotal Phase IIb obesity trial showed no statistically significant weight loss versus placebo ^[5]. The development program was discontinued around 2007 ^[14]. That is the part the popular "fat-loss peptide" marketing tends to skip. The receptor-sparing safety story held up; the fat-loss story, in humans, did not. Everything on this site keeps that distinction in plain view.

What it is — and what it is not

AOD-9604 is a fragment of growth hormone, not growth hormone itself, and not a secretagogue (a compound that makes your body release its own GH — that is what CJC-1295, ipamorelin, and sermorelin do; AOD-9604 does not). It is not a steroid. It is not a dietary supplement, even though it shows up next to supplement searches. And it does not raise IGF-1, by design ^[3].

What it is: an investigational research peptide with a clean mechanistic idea, a solid preclinical record, a clean human safety profile, and a null human efficacy result. This digest covers the AOD-9604 research in depth, the reported AOD-9604 effects, the doses studied across species, and the most-asked questions — every quantitative claim cited to its source in the AOD-9604 references.