Peptides/Weight and appetite
AOD-9604
Also sold as Anti-Obesity Drug 9604, HGH fragment 176-191
A growth hormone fragment that reached a proper phase 2b trial, which makes it one of the few compounds here with a real answer.
At a glance
What people use it for
- Marketed for fat loss without affecting blood sugar
- Sold in weight loss injection blends
- Promoted for stubborn fat around the middle
How it is taken
Sold as a powder for injection, and sometimes in oral or topical forms.
Evidence
Early human studies
Best known for
- One of very few compounds here with a completed human efficacy trial
- Showed no signal of the blood sugar problems growth hormone causes
- Reported as well tolerated in phase 2 work
- Research attention has since moved to cartilage and joint health
AOD-9604 is a small piece cut out of human growth hormone, specifically the tail end that seemed responsible for breaking down fat. The appeal was obvious: the fat-burning effect of growth hormone without the effects on blood sugar and tissue growth.
It reached human trials, which puts it ahead of most compounds in this section, and it is one of the few here where the story has an ending.
Why people are talking about it
The design idea is genuinely good. Growth hormone does several things, and only one of them is wanted here. Cutting out the fragment responsible for the fat effect and leaving the rest behind is exactly the kind of thinking that produces useful medicines.
And the safety half of that idea worked. The trials found no signal of the blood sugar problems growth hormone itself causes, which was the specific thing the design was meant to avoid.
What people take it for
Fat loss, principally, and particularly abdominal fat. It appears frequently in injectable weight loss blends alongside other ingredients.
Fat loss without the blood sugar effects
The claim is mobilising stored fat without growth hormone's metabolic downsides. The mechanism proposed is stimulation of lipolysis, the breakdown of stored triglycerides, through a route that does not involve the growth hormone receptor's other actions.
In practice that describes separating one of growth hormone's effects from the rest. That separation is what the compound was built to test.
What the evidence shows
This is the unusual case where a research peptide was actually tested and the answer came back. A phase 2b trial ran AOD-9604 against placebo in obese adults for 12 weeks. Weight loss did not separate meaningfully from placebo, and development for obesity did not continue.
The phase 2 work reported it as generally well tolerated, with no signal of the blood sugar problems growth hormone itself causes. That is a real finding, and it is the part of the programme that succeeded.
Later work has looked at it for cartilage and joint health instead, which is where the research attention has moved. That work is early and mostly preclinical.
How it is taken
Sold as a powder for reconstitution and subcutaneous injection. Oral and topical versions are also sold, and a peptide of this size is not expected to survive digestion or cross intact skin in meaningful quantity.
It appears often in blends, which is worth knowing when reading a label: several ingredients in one vial makes it impossible to attribute anything to one of them.
How it compares
Against HGH Frag 176-191
HGH Frag 176-191 is this molecule without the added tyrosine residue that stabilises it. They differ by one residue, so the trial result for AOD-9604 is the most relevant evidence there is for both.
Against the GLP-1 drugs
Semaglutide and tirzepatide work through appetite and produced large, replicated results in trials of the same design that AOD-9604 went through. The comparison is instructive: same kind of trial, very different answers.
Common questions
Did it work?
Not for weight loss. The phase 2b trial found no meaningful separation from placebo over 12 weeks.
Is it safe?
The trial reported it as well tolerated, and specifically without the blood sugar effects growth hormone causes. Long-term use has not been studied.
Why is it still sold?
The mechanism story is appealing and the animal literature is real. The trial result is the part usually left out.
What is it being researched for now?
Cartilage and joint health, which is early-stage work and unrelated to the fat loss marketing.
Last reviewed .