00 // Research ledger — hGH 176-191 fragment
AOD-9604 is the hGH 176-191 fat-metabolism fragment that spares the growth-hormone receptor.
Strong preclinical lipolysis on one line; a null human obesity trial on the next. Every figure here is posted to a study.
The short version
AOD-9604 is a small lab-made peptide — a short chain of amino acids. It copies the last piece of human growth hormone, the part that handles fat. In fat cells it tells the cell to stop building new fat (lipogenesis, the making of fat) and to burn more of it [1][3]. The trick is that it skips growth hormone's receptor (the docking port a hormone plugs into), so it does not raise IGF-1 (a growth signal) the way growth hormone does [3]. That is the promise. The honest part: in people it did not work. Across about six trials in roughly 900 adults with obesity, AOD-9604 did not beat a placebo for weight loss, and the company stopped the program around 2007 [5][12][14]. Most of the fat-burning evidence is from mice and test tubes [1][2][3]. It is not approved, it is not a supplement, and athletes should know it is banned in sport [15]. What people report — including how little they noticed — is on the effects page.
AOD-9604: what the record shows
AOD-9604 (Anti-Obesity Drug 9604) is a synthetic 16-amino-acid peptide modelled on the C-terminal region of human growth hormone — residues 176/177-191 — with an N-terminal tyrosine added [3]. Its reported sequence is Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe, molecular weight 1815.1 Da, CAS 221231-10-3. Two cysteines form a disulfide bridge that mirrors the cystine loop of the parent hormone [3].
In fat cells the fragment does two measured things. It inhibits acetyl-CoA carboxylase (ACC) — the rate-limiting enzyme that builds new fat — through a membrane-derived second messenger, cutting de novo fat synthesis [4]. And it up-regulates beta-3 adrenergic receptor (beta3-AR) expression in white adipose tissue, the receptor that drives fat breakdown and energy use [1]. After 14 days of chronic dosing, obese mice lost body weight and fat and showed higher beta3-AR RNA [1]. The same direction held in a second mouse model, with increased fat oxidation and weight loss [2].
The design point is what AOD-9604 does not do. It does not bind the growth-hormone receptor, so it does not raise IGF-1 and does not carry growth hormone's growth or insulin-resistance effects [1][3]. That is the gh-receptor-sparing claim this site reads line by line.
The human column does not foot
The rodent ledger balanced; the human ledger did not. Across roughly six randomised, double-blind, placebo-controlled trials totalling about 900 obese adults, oral AOD-9604 at daily doses from 0.25 mg to 54 mg (durations from 7 days to 24 weeks) was reported as well tolerated — its safety profile was indistinguishable from placebo and free of the adverse effects tied to full-length growth hormone [5]. But the pivotal Phase IIb obesity trial did not show statistically significant weight loss versus placebo, and Metabolic Pharmaceuticals discontinued the obesity program around 2007 [12][14].
That is the honest core of the story. The popular framing of AOD-9604 as a proven "fat-loss peptide" runs far ahead of the human evidence, which is null [12][13]. Strong preclinical data did not translate — a common outcome for obesity drug candidates [13][14]. This site keeps both entries on the books: the real preclinical lipolysis, and the human result that did not beat placebo. The full picture of what people report is on AOD-9604 effects.
A distinction worth posting first
AOD-9604 is a fragment of growth hormone, not growth hormone itself. Because it is only the C-terminal 176-191 piece (plus the added tyrosine), it does not act like the whole hormone — it is gh-receptor-sparing [1][3].
It is also not a secretagogue. CJC-1295, ipamorelin, and sermorelin make the body release more of its own growth hormone; AOD-9604 does neither — it is a standalone fat-metabolism fragment [3]. And it is not a steroid. It carries no androgenic mechanism. Despite the "fat-loss peptide" and supplement adjacency online, AOD-9604 is not a dietary supplement and not an approved drug [14]. For the full breakdown, see what is aod9604 and the AOD-9604 side effects record.