AOD-9604 Research Guide: GH Fragment, Lipolysis Mechanisms, and Metabolic Research

By Justin Cartier

For the wider context, see our overview of research peptides for weight loss.

AOD-9604 is a small 16-amino-acid piece of human growth hormone (HGH), studied for one thing: burning fat. This peptide fragment copies the fat-burning part of HGH but skips the rest, so it doesn’t bind the main HGH receptor and doesn’t raise IGF-1.^[1] This guide walks through what AOD9604 is, how it works, what the studies show on weight loss, how it compares to other fat-loss peptides, and what to check when sourcing it.

The reason it was built this way is pretty simple. Full HGH makes a messy weight tool, since it drags along insulin resistance, growth-related risks, and other side effects. So researchers at the Howard Florey Institute in Melbourne designed this peptide derived from HGH to keep only the fat-burning piece, residues 177 to 191, and leave everything else behind. It actually made it all the way to large human Phase 3 obesity trials, but it didn’t show enough weight loss in the broad population, so it settled into life as a research tool rather than an approved drug. In rodents the fat-loss results were stronger, and that gap between strong animal data and modest human data is a familiar pattern across metabolic peptide research.

Research-use disclaimer: AOD-9604 is sold for laboratory research only. It isn’t a drug, supplement, or treatment, and it isn’t for human use. The notes below describe published lab, animal, and clinical research, not medical advice.

What is AOD-9604 and how does it work?

At its core it’s a lab-made copy of the fat-burning part of human growth hormone. Ng and colleagues, in Hormone Research, describe how AOD9604, spanning residues 177 to 191, was designed specifically to pull HGH’s fat-specific effects away from its broader growth effects.^[1] A disulfide bond and a free tyrosine on the fragment are what give it that fat-specific action.

The receptor side is where it really diverges from HGH. Heffernan and colleagues, in the International Journal of Obesity, showed the fragment doesn’t compete for the HGH receptor and doesn’t make cells multiply, which sets it apart from full HGH and the IGF-1-based options.^[2] Instead it takes a separate route onto the fat cells, driving fat breakdown without the broad muscle-building and cell-growth effects that come with HGH.

Lipolysis mechanism: HSL and ACC

The actual fat-burning comes down to two enzymes inside the fat cell. Ng and colleagues, in the Journal of Molecular Endocrinology, showed a closely related analog switching on hormone-sensitive lipase (HSL) and switching off acetyl-CoA carboxylase (ACC) in fat cells.^[3] HSL is the enzyme that breaks stored fat down for energy, while shutting off ACC slows the very first step of making new fat. Burn more while making less, and you get the net fat-loss effect. Heffernan and colleagues, in the American Journal of Physiology, found the parent compound cut lipogenesis and raised fat oxidation in tissue, with the fragment carrying that same two-part action in a refined form.^[4] And Wu and colleagues, in Biochemistry and Molecular Biology International, pinned the fat-blocking part of HGH to the C-terminal region, which is exactly the design logic behind the fragment.^[5]

Does AOD-9604 really work for weight loss?

It works, but let’s be honest about the size of it, which is small. Phase 2 human trials in obese participants showed about 2.6 kg of weight loss over 12 weeks at the best dose (1 mg per day), against 0.8 kg on placebo. That’s a fraction of what the GLP-1 drugs deliver, where semaglutide gives around 14.9 percent over 68 weeks and tirzepatide about 20.9 percent over 72 weeks. AOD9604 simply didn’t clear the bar for FDA approval as a weight-loss drug, which is a big part of why no finished product exists.

How much weight can you lose on AOD-9604?

Going by the clinical data, weight loss over 12 to 24 weeks lands somewhere in the 2 to 5 kg range, and most of it comes off as fat rather than muscle. So the body composition shift is genuinely good, fat-specific burning with the muscle preserved, even though the total number on the scale stays small. For research into how fat burning actually works, that modest change is perfectly fine; for big weight-loss endpoints, the GLP-1 class runs circles around it.

How does AOD-9604 compare to other fat-loss peptides?

The fat-loss peptide field really breaks into a few mechanism classes. The GLP-1 receptor agonists like semaglutide and liraglutide cut appetite and slow the stomach for roughly 10 to 15 percent weight loss. The GIP/GLP-1 dual agonist tirzepatide layers GIP on top of that for about 20 percent at the top dose. The triple agonist retatrutide then adds glucagon-receptor action for extra energy burn, reaching around 24 percent. Off in a different lane, the GHRH analog tesamorelin drives GH-mediated belly-fat loss, trimming visceral fat by 15 to 18 percent. And 5-Amino-1MQ blocks the NNMT enzyme to burn cellular energy, though its data is still rodent-only. AOD9604 sits at the bottom of that list on raw effect, a modest 2 to 5 kg total, but it also has the cleanest, most direct fat-cell mechanism of the bunch. That makes it a research tool for studying fat-burning biology, not a primary weight-loss therapy.

Dosage and administration

The published Phase 2 trials ran AOD9604 at 1 mg per day, either by mouth or by subcutaneous injection, while research protocols span 300 micrograms to 1 mg per dose. It comes as a freeze-dried powder that you mix with bacteriostatic water. One of its quirks is that it holds some oral activity, which few peptides manage, though injection gives steadier blood levels for research work.

Side effects and safety

The safety record is genuinely good. The reported side effects in clinical and research use are minimal, mostly the occasional mild injection-site irritation and the rare brief headache, with no recorded liver, heart, or body-wide safety signals. Because the fragment doesn’t touch IGF-1, glucose, or growth measures, it sidesteps the GH-related side effects of HGH itself. All told, AOD9604 was considered broadly safe across the Phase 2 obesity trial program.

When is AOD-9604 a poor fit?

There are a handful of situations where the fragment is a poor research fit, or at least calls for caution. Pregnancy and breastfeeding are off the table on insufficient safety data. Active cancer is a precautionary exclusion, even though no cell-growth signal has ever been recorded. A history of severe low blood sugar warrants care, given the fragment’s rare effect on glucose handling, and so does any known sensitivity to the peptide components. Beyond those, anyone hoping for big weight loss should keep in mind that AOD9604 just doesn’t match the effect sizes of the GLP-1 drugs. Researchers studying fat-burning pathways are really the main appropriate use case.

When can you expect to see results?

In the clinical research, body-weight curves start pulling away from placebo within 4 to 6 weeks of steady dosing, and the effect keeps building through 12 to 24 weeks. The body composition changes, meaning more of the loss coming from fat, tend to show up on DEXA scans within 8 to 12 weeks. The effects on energy and appetite are minimal, so the mechanism stays quiet at the level of how you actually feel.

Is AOD-9604 legal?

AOD-9604 isn’t approved as a finished drug by Health Canada, the FDA, or the EMA (though it holds Generally Recognized As Safe status in some US food settings, which is separate from weight-loss drug rules) and is sold as a research-use-only chemical; our guide to buying peptides in Canada covers how these rules work.

Red flags to watch for when sourcing AOD-9604

A few warning signs flag a bad batch before it ever reaches your bench. Start with the paperwork: no independent lab report specific to that production lot, or a vague one that gives a purity number with no matching batch code, is a reason to pass. Next, distrust a lone HPLC figure like “98 percent” that arrives with no chromatogram trace, because the trace is what proves one clean peak rather than a spread of truncated side-products. The sharpest check is the mass: AOD-9604 is a 16-amino-acid fragment with a disulfide bond and an expected weight near 1,815 Da, so an MS readout that misses that number, or a spectrum that hints the disulfide bond never formed, means the vial doesn’t hold intact peptide. For any in-vivo or cell-culture work, missing endotoxin and sterility data is the last deal-breaker.

Reviv Peptides supplies AOD-9604 with a third-party COA and HPLC purity confirmation. View the AOD-9604 5mg product page.

AOD-9604 questions

Does AOD-9604 really work for weight loss?

Yes, but with small effects. Phase 2 data showed 2.6 kg of weight loss over 12 weeks at 1 mg per day, mostly from fat rather than muscle. The effect is much smaller than the GLP-1 drugs or other modern weight-loss peptides.

How much weight can you lose on AOD-9604?

Expected weight loss is in the 2 to 5 kg range over 12 to 24 weeks, mostly from fat. The body composition shift is good, but the total weight drop is small compared with the GLP-1 drugs.

When is AOD-9604 a poor fit?

Pregnancy, breastfeeding, active cancer, a history of severe low blood sugar, and known peptide sensitivity. Studies that need large weight-loss effects are better matched to the GLP-1 class.

What is AOD-9604 and how does it work?

It’s a 16-amino-acid fragment of human growth hormone (residues 177 to 191) that burns fat without binding the HGH receptor or raising IGF-1. It works by switching on hormone-sensitive lipase and switching off acetyl-CoA carboxylase in the fat cells.

Is AOD-9604 safe?

The safety record is good. Phase 2 trials showed minimal side effects, no liver or heart signals, and no IGF-1 or growth-related effects. It doesn’t cause the GH-related side effects of full HGH.

Key data point: Heffernan and colleagues (2001, International Journal of Obesity) reported that this HGH fragment raised fat oxidation and drove weight loss in obese mice without competing for the HGH receptor,^[2] which is the finding that anchors AOD9604’s reputation as a fat-specific tool free of the usual GH-axis effects.

Summary

AOD-9604 is a 16-amino-acid fragment of human growth hormone, built to keep HGH’s fat-burning action while dropping its broader growth effects. It switches on hormone-sensitive lipase and switches off acetyl-CoA carboxylase in the fat cells, all without binding the HGH receptor or raising IGF-1. The clinical weight-loss effect is small, about 2 to 5 kg over 12 to 24 weeks, far short of the GLP-1 drugs. It never won FDA approval for weight loss, though it carries GRAS status in some food settings. For anyone studying fat-burning biology without GH-axis confounds, AOD9604 is one of the cleanest tool peptides in the category, and it remains available for research use under research-use-only labels.

Sources: [1] Metabolic studies of AOD9604, the synthetic lipolytic domain of hGH (Ng et al., 2000), PubMed. [2] HGH fragment increases fat oxidation and weight loss without HGH-receptor effects (Heffernan et al., 2001), PubMed. [3] HGH structural domain action on lipid metabolism, HSL/ACC (Ng et al., 2000), PubMed. [4] Synthetic HGH fragment on lipid metabolism (Heffernan et al., 2000), PubMed. [5] Antilipogenic C-terminal sequence 177-191 of hGH (Wu et al., 1993), PubMed.

Justin Cartier

The Reviv Peptides Research Team is a collective of science writers and researchers dedicated to producing evidence-based, peer-reviewed-grade content about research peptides. Our work focuses on molecular mechanisms, receptor pharmacology, and preclinical data — including GLP-1/GIP/glucagon incretin biology, growth hormone axis peptides (GHRH analogs and ghrelin-receptor secretagogues), mitochondrial-derived peptides (MOTS-c, SS-31), tissue-repair peptides (BPC-157, TB-500, GHK-Cu), and nootropic peptides (Semax, Selank). All content is written in a strict preclinical/laboratory context; none of our editorial material is intended as medical advice. Every guide is reviewed for scientific accuracy against published peer-reviewed literature.