HGH fragment 176-191
hGH frag, Frag 176-191, Lipolytic fragment
The tail end of the growth hormone molecule, sold on the premise that it burns fat without growth hormone's downsides. Its optimised drug version failed a proper phase 2b trial.
Preclinical only
Not approved anywhere. The related analogue AOD-9604 was developed as an obesity drug, failed its pivotal trial and was abandoned in 2007. Both are sold as research material.
What it is
Growth hormone is 191 amino acids long. Work in the 1990s suggested that its fat-metabolising activity sat in the C-terminal region, and that a short fragment of that region, residues 176 to 191, might reproduce the lipolytic effect without the growth-promoting one.
That is an attractive premise. Growth hormone's problems in healthy adults, insulin resistance, oedema, joint pain, carpal tunnel, tissue growth, come from its anabolic signalling. A fragment that only burned fat would be a genuinely useful drug.
Somebody tested that premise properly, and it did not work
Metabolic Pharmaceuticals developed AOD-9604, a modified and stabilised version of this fragment, specifically as an obesity treatment. It went through the real process.
An early twelve week study looked encouraging, with about 2.6 kg lost against 0.8 kg on placebo. The pivotal trial was a 24 week, placebo-controlled phase 2b in 536 subjects, adequately powered to detect weight loss.
It missed. The best-performing dose group lost about 2.6 kg against 1.8 kg for placebo, a difference that was not statistically significant. Development was terminated in 2007.
The primary publication from that phase 2b was never submitted to a peer-reviewed journal, which is its own kind of information. Negative results are much less likely to be written up than positive ones, and the absence of the paper is part of why the compound still gets marketed as promising two decades later.
Why it is still sold
Because the mechanism story is appealing and the failed trial is easy not to mention.
Vendor material for this fragment routinely cites the early rodent work and the twelve week study, and routinely omits the larger trial designed to confirm them. A reader encountering only the first half of that sequence would reasonably conclude the compound works.
This is the pattern the methodology page describes as the most common failure mode in this space, and it is unusually clean here: the confirmatory trial exists, it was properly designed, and it was negative.
Practical notes
- The fragment you can buy is not the compound that was tested. AOD-9604 was a stabilised analogue. The unmodified 176-191 fragment has even less human evidence, which is a strange position for the version that failed to be the better-studied one.
- The absence of side effects is not a safety finding. Very little is reported, and very little has been looked for outside the AOD-9604 programme.
- If the goal is fat loss, the honest comparison is unflattering. The incretin class produces double-digit percentage weight loss in published trials. This produced a non-significant kilogram over placebo in the one trial built to find out.
Side effects and warning signs
Commonly reported
- Injection-site irritation
- Headache, occasionally reported
- Notably few reported effects, which reflects how little it appears to do rather than an established safety profile
Stop and get medical help
- No systematic human safety dataset exists for the unmodified fragment, so absence of reported harm reflects absence of study
Sources
From the community
Discussion for this compound concentrates in r/Peptides.
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