Research digest // growth-hormone fat-loss fragment
AOD-9604 is a growth-hormone fat-loss fragment whose pivotal human trial fell flat.
A patient, plain-English digest of what the studies measured — the strong rodent fat-metabolism data, the human obesity trial that did not beat placebo, and the line where the marketing outruns the evidence.
The short version
Here is AOD-9604 in plain words. It is a small piece — a fragment — of human growth hormone, the part of that hormone that deals with fat. Scientists call it hGH fragment 176-191. The idea was clever: keep growth hormone's fat-handling action, but leave out the parts that make you grow or raise blood sugar. In mice and rats it worked. It told fat cells to make less new fat and to burn more, and it did this without touching the growth-hormone receptor (the cell's "on switch" for growth hormone), so it did not raise IGF-1 (a growth signal that full growth hormone sends).
Then the company that owned it gave it to about 900 overweight adults. The main trial did not beat a placebo (a dummy treatment). People taking AOD-9604 lost no more weight than people taking nothing. The program was shelved. So the honest picture is this: a strong story in animals, a flat result in humans. AOD-9604 is investigational — not an approved medicine, and not a supplement. What people report, including the downsides, is on the effects page.
What is aod9604
AOD-9604 is a synthetic 16-amino-acid peptide modelled on the tail end (the C-terminal region) of human growth hormone, residues 177-191, with an extra tyrosine added at one end [3]. Its job in the body's design was narrow: reproduce the fat-metabolising part of growth hormone without the rest of it. The foundational laboratory work, done in the 1980s and refined through the 1990s and 2000s, traced growth hormone's effect on fat to exactly this region of the molecule [3] [4].
The distinction that matters most is this: AOD-9604 is a fragment of growth hormone, not growth hormone itself, and not a compound that tells your body to release its own growth hormone. That sets it apart from the growth-hormone-releasing peptides such as CJC-1295, ipamorelin, and sermorelin, which work the other way around by prompting natural release. AOD-9604 does not bind the growth hormone receptor at all, and it does not raise IGF-1 [1] [3]. It is also not a steroid, and despite how it is often sold, it is not a dietary supplement.
AOD9604 peptide
As a peptide, AOD-9604 has a defined structure: the sequence YLRIVQCRSVEGSCGF, a molecular weight of about 1815.1 Da, and an internal disulfide bridge between its two cysteine residues that mirrors a loop in the parent hormone [3]. The two ways it changes fat metabolism in animal studies are well characterised. First, it inhibits lipogenesis (the making of new fat) by blocking an enzyme called acetyl-CoA carboxylase, the rate-limiting step in fatty-acid synthesis [4]. Second, it nudges up the beta-3 adrenergic receptor (a switch on fat cells that, when flipped, drives fat-burning and energy use), restoring suppressed levels in obese mice back toward those of lean mice [1].
The AOD9604 peptide is rapidly cleared from the body. After intravenous injection in an animal pharmacokinetic model, its half-life was roughly 3 minutes, and the intact peptide breaks down quickly by losing amino acids one at a time from its leading end [6]. The human program tested it as an oral tablet, the form it was designed for.
Why the human result is the whole story
Across roughly six randomised, double-blind, placebo-controlled trials run by Metabolic Pharmaceuticals through the 2000s — about 900 overweight adults in total, on oral doses from 0.25 mg up to 54 mg per day for between 7 days and 24 weeks — AOD-9604 was well tolerated, with side effects hard to tell apart from placebo [5]. That is the good news, and it is real.
The problem is that tolerability is not efficacy. The pivotal Phase IIb obesity trial did not produce statistically significant weight loss versus placebo, and the obesity development program was discontinued around 2007 [10]. The compound was never approved for any indication [9]. Reviews of the obesity-drug landscape now list lipolytic growth-hormone-fragment approaches like AOD-9604 among the many candidates that looked promising in the lab and did not deliver a proven clinical benefit [8] [10]. If you read only the marketing, you would never know this trial happened. The whole point of this site is that it did.
How to read the rest of this site
This digest is organised the way a careful reader would want it. The AOD-9604 research page walks through the mechanism and the key studies, tagging every finding as preclinical (animal or cell) or human so you never mistake a mouse result for a person result. The AOD-9604 weight loss and AOD9604 results pages lead with the null human trial, plainly, because that is what an honest summary of efficacy requires. The AOD-9604 effects page collects what the research-use community reports — clearly labelled as anecdote, not evidence — alongside cited safety cautions. The dosage page reports only what was studied, in which species, by which route — never a human dose. And every quantitative claim here links to a numbered source on the AOD-9604 references page.