A stabilized fragment of human growth hormone encompassing the lipolytic C-terminal domain, developed to produce fat loss without the anabolic or diabetogenic effects of HGH.
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Buy Now →AOD-9604 is a synthetic peptide fragment derived from the C-terminal end of human growth hormone (hGH). Specifically, it corresponds to amino acids 177 through 191 of the hGH sequence, with one important structural modification: a tyrosine residue has been added to the N-terminus of the fragment. This addition stabilizes the peptide and improves its biological activity, which is why you’ll sometimes see it referenced as Tyr-hGH 177-191 in the scientific literature.
The compound was developed at Monash University in Melbourne, Australia, by a research team led by Professor Frank Ng during the 1990s. The original goal was elegantly straightforward — identify the portion of the growth hormone molecule responsible for its fat-burning effects while stripping away everything that caused unwanted growth promotion, insulin resistance, and the broader endocrine disruption associated with exogenous hGH use. That effort produced AOD-9604.
What makes AOD-9604 genuinely interesting from a research standpoint is that it appears to retain the lipolytic (fat-breaking) signaling capacity of full-length growth hormone without triggering the anabolic cascade that makes whole GH so complicated to study in clinical settings. It does not stimulate IGF-1 production to any meaningful degree, and multiple studies have confirmed that it does not impair glucose tolerance or insulin sensitivity — two major concerns with conventional GH therapy.
In Australia, the Therapeutic Goods Administration (TGA) has classified AOD-9604 as a food-grade ingredient under specific regulatory provisions, which distinguishes it from most peptide research compounds. Metabolic Pharmaceuticals, the company that commercialized the Monash University research, pursued extensive clinical development through Phase I, II, and Phase III trials for obesity treatment under the brand name Adipotide (not to be confused with a separate compound of that name). While the obesity indication did not ultimately achieve regulatory approval at the Phase III stage due to insufficient weight-loss magnitude, the safety profile established across those trials has been consistently favorable.
AOD-9604 is sometimes called the “anti-obesity peptide” in research circles, and while that framing oversimplifies what the compound actually does mechanistically, it captures the core focus of the research base. Current investigation has also expanded to include its potential role in cartilage repair and regeneration, giving the peptide a broader research profile than its origins in metabolic science might suggest. You can explore related compounds in our peptide database.
The primary mechanism through which AOD-9604 drives lipolysis involves its interaction with beta-3 adrenergic receptors (β3-AR), which are expressed predominantly in adipose tissue — both white and brown fat depots. When AOD-9604 binds to or activates signaling downstream of this receptor class, it triggers a cascade that ultimately increases cyclic AMP (cAMP) levels within adipocytes. Elevated intracellular cAMP then activates protein kinase A (PKA), which phosphorylates and activates hormone-sensitive lipase (HSL). Activated HSL cleaves stored triglycerides into free fatty acids and glycerol, which are then released into circulation for use as energy substrates. This is the core biochemical sequence that gives AOD-9604 its fat-mobilizing properties. Importantly, this pathway operates largely independently of insulin signaling pathways, which explains why AOD-9604 does not produce the insulin resistance seen with full-length hGH. The β3-AR pathway is also the target of several pharmaceutical obesity compounds, making AOD-9604’s activity in this space mechanistically coherent with broader drug development strategies in the metabolic disease field.
Beyond PKA-mediated HSL activation, AOD-9604 research has pointed to a secondary regulatory effect involving acetyl-CoA carboxylase (ACC), a key enzyme in de novo lipogenesis — the cellular process of synthesizing new fatty acids from non-fat precursors. ACC catalyzes the conversion of acetyl-CoA to malonyl-CoA, the first committed step in fatty acid synthesis. Inhibition of ACC reduces malonyl-CoA levels, which in turn disinhibits carnitine palmitoyltransferase I (CPT-I), the enzyme responsible for transporting long-chain fatty acids into mitochondria for beta-oxidation. In practical terms, this means AOD-9604 may simultaneously increase fat mobilization from storage (via HSL activation) while also enhancing the cellular machinery for oxidizing those released fats as fuel. This dual action — lipolysis plus enhanced fatty acid oxidation — creates a more comprehensive fat-reducing effect than simple lipolysis stimulation alone would produce. Research by Ng and colleagues at Monash University provided the foundational evidence for these enzyme-level effects in adipocyte cell culture and animal model systems.
One of the most scientifically important aspects of AOD-9604’s mechanism is what it does not do. Full-length growth hormone exerts its anabolic and metabolic effects through two distinct pathways: direct GH receptor activation in target tissues, and indirect effects mediated by the induction of IGF-1 from the liver. The anabolic (muscle-building, bone-growing) effects of hGH are substantially mediated by IGF-1, while the lipolytic effects appear to involve more direct adipocyte signaling. AOD-9604, as a C-terminal fragment, lacks the receptor-binding domain of hGH required to stimulate the liver’s IGF-1 production. Binding studies have confirmed that AOD-9604 does not bind to the GH receptor with any functional affinity. This mechanistic separation is what gives the peptide its favorable safety profile — it activates fat mobilization signaling without engaging the growth-promoting, glucose-impairing, or proliferative pathways that make whole hGH a challenging molecule in clinical and research contexts.
The foundational research establishing AOD-9604’s properties was published by Ng, Kusunoki, and colleagues from Monash University across the late 1990s and early 2000s. These studies used obese animal models — primarily the ob/ob mouse — to demonstrate that the C-terminal hGH fragment produced dose-dependent reductions in body fat without the hyperglycemia, organ enlargement, or IGF-1 elevation seen with full-length hGH administration. A particularly notable finding was that AOD-9604’s fat-reducing effect was additive with caloric restriction rather than simply mimicking it, suggesting a mechanistically distinct pathway rather than a simple reduction in food intake. The peptide did not increase lean mass, confirming the absence of anabolic signaling. Growth plate examination in juvenile animals did not show the accelerated ossification seen with hGH, providing anatomical confirmation that the compound was not engaging growth-promoting pathways. These early studies established the scientific foundation that justified advancing AOD-9604 into human clinical trials and remain the most frequently cited evidence base for the compound’s lipolytic selectivity.
Metabolic Pharmaceuticals conducted a formal clinical development program for AOD-9604 as an anti-obesity treatment. Phase I trials established safety and pharmacokinetics in healthy volunteers, confirming the compound’s tolerability at a range of doses administered via subcutaneous injection. Phase II studies examined efficacy signals in overweight and obese participants across multiple dosing regimens, including oral and injectable forms, over study periods of 12 to 24 weeks. Results from Phase II showed statistically significant fat loss compared to placebo in some dosing cohorts, though effect sizes were modest. Critically, none of the Phase I or II studies identified adverse effects on fasting glucose, HbA1c, insulin sensitivity, IGF-1 levels, or standard safety biomarkers, reinforcing the mechanistic predictions from the animal data. The Phase III program, while not achieving its primary endpoint for the injectable formulation in terms of meeting the regulatory bar for approvable weight loss magnitude, generated an extensive human safety dataset. No serious adverse events attributable to AOD-9604 were identified, and the compound was well-tolerated across thousands of participant-treatment-weeks of exposure.
A particularly compelling line of AOD-9604 research has investigated whether the peptide can be absorbed through oral administration, which would represent a significant practical advantage over injectable delivery. Most peptides are rapidly degraded by gastrointestinal proteases before meaningful systemic absorption can occur, but AOD-9604’s relatively short chain length and specific structural features prompted investigation of oral bioavailability. Clinical studies comparing oral to injectable AOD-9604 found that, while oral bioavailability was lower than subcutaneous injection, measurable systemic exposure was achievable with oral dosing. Some Phase II trial arms specifically evaluated oral AOD-9604 formulations and found evidence of biological activity in terms of fat loss, though this area of the research is less thoroughly published in the peer-reviewed literature than the injectable work. The TGA’s classification of AOD-9604 as a food supplement ingredient in Australia is partly informed by this oral administration research and the compound’s established safety profile at doses used in oral form.
More recent research has extended AOD-9604’s investigated applications beyond fat metabolism into musculoskeletal tissue repair, particularly cartilage. Studies conducted primarily in in vitro cell culture systems and small animal models have examined whether AOD-9604 can stimulate chondrocyte (cartilage cell) activity and support extracellular matrix synthesis. These investigations have found that AOD-9604 can stimulate proteoglycan synthesis in chondrocyte cultures — a meaningful finding because proteoglycans are structural components of healthy cartilage that are lost in degenerative joint conditions like osteoarthritis. Animal model studies using surgically induced cartilage defects found that AOD-9604 administration was associated with improved cartilage repair scores compared to control groups. While this work is considerably earlier-stage than the metabolic research, it has attracted attention because it suggests the peptide might have utility in joint health research — a mechanistically logical area given that GH and IGF-1 are known to support cartilage maintenance, and AOD-9604’s activity may include some partial engagement with pathways relevant to connective tissue health.
Several studies have examined whether AOD-9604’s fat-reducing effects are accompanied by changes in other body composition parameters. The consistent finding across both animal and human research is that lean mass is preserved or unchanged — AOD-9604 does not produce the lean mass gains seen with anabolic agents, but it also does not cause the muscle wasting sometimes associated with severe caloric restriction. Bone mineral density measurements in clinical trials did not show significant changes over the trial periods studied, consistent with the absence of IGF-1 elevation. Water retention, a common side effect of full hGH that can significantly complicate body composition interpretation, was not observed in AOD-9604 research cohorts. This body composition profile — selective fat reduction with lean mass preservation and no fluid retention — is considered a desirable research target for metabolic intervention studies where clean isolation of fat mass changes is methodologically important.
The clinical trial program for AOD-9604 tested a range of doses across different administration routes and study designs. For subcutaneous injection, published Phase II data examined doses from approximately 250 mcg to 1,000 mcg per day, with a 500 mcg once-daily dose emerging as a common reference point across efficacy studies. Oral dosing studies tested substantially higher nominal doses (in the range of 1,000 mcg to 9,000 mcg per day) to account for the reduced bioavailability of the oral route. These dose ranges reflect research protocols and are provided for informational context about the published literature, not as guidance for any particular application. Our peptide calculators can help with reconstitution and dosing math for research reference purposes.
AOD-9604 has been studied via both subcutaneous injection and oral administration. Subcutaneous injection provides more predictable and complete systemic delivery, while oral delivery offers convenience at the cost of lower and more variable bioavailability. Research protocols using injectable AOD-9604 typically involved single daily administrations, often timed in the morning in a fasted state to align with endogenous growth hormone pulsatility patterns and to avoid interaction with postprandial insulin levels. The reconstitution of lyophilized AOD-9604 for injection follows standard peptide preparation practices, using bacteriostatic water and refrigerated storage after reconstitution.
Clinical trials examining AOD-9604 for fat loss used study durations ranging from 12 weeks to 24 weeks of continuous daily administration. The 12-week timeframe was the minimum period over which meaningful fat loss signals were observed in the clinical data. Longer study durations did not appear to produce receptor downregulation or loss of effect in published data, though the evidence base for very long-term continuous administration is limited. Protocols combining AOD-9604 with dietary modification showed additive effects in some trial arms, suggesting that metabolic state and dietary context influence the compound’s observable impact.
Like most synthetic peptides, AOD-9604 in lyophilized (freeze-dried) powder form is relatively stable at room temperature for short periods but should be stored refrigerated (2-8°C) for longer-term preservation. Reconstituted solution should be kept refrigerated and used within a reasonable timeframe — typically cited as 2-4 weeks when stored properly with bacteriostatic water as the diluent. The peptide should be protected from light and repeated freeze-thaw cycles, which can degrade peptide integrity. These are standard considerations for any research-grade peptide preparation.
AOD-9604’s safety profile is better characterized than virtually any other research peptide currently under investigation, largely because it progressed through a formal pharmaceutical clinical trial program that generated extensive, systematically collected safety data. Across Phase I, II, and III trials, the compound did not produce serious adverse events attributable to the study drug. Common adverse events reported were generally mild and included injection site reactions (the most frequently noted), headache, and gastrointestinal discomfort at higher oral doses. The most clinically important safety findings — blood glucose, insulin sensitivity, IGF-1, lipid panels, liver enzymes, kidney function markers, blood pressure, and cardiac parameters — remained within normal ranges across all studied dose cohorts and durations. This stands in significant contrast to full-length hGH, which reliably causes measurable insulin resistance at research doses and requires careful monitoring in any human study.
While AOD-9604’s safety profile is favorable within the studied parameters and time horizons, important caveats apply to interpreting this data. The longest published clinical studies ran approximately 24 weeks, meaning very long-term safety beyond that window is not well characterized in humans. The Phase III trial failure on efficacy endpoints also means that the research and regulatory interest needed to fund larger, longer safety studies has not materialized in the way it might have for an approved pharmaceutical. Additionally, while the absence of IGF-1 elevation is mechanistically reassuring from a proliferative safety standpoint, the cartilage repair research introduces some complexity — if the compound does modulate growth factor pathways in specific tissue contexts, that warrants continued investigation rather than blanket dismissal. Users should be aware that regulatory status varies significantly by jurisdiction, and the Australian TGA food supplement classification does not automatically apply globally.
No formal contraindications have been established for AOD-9604 based on published clinical data, in part because the compound has not been approved as a pharmaceutical in any major regulatory jurisdiction, meaning the comprehensive contraindication and drug interaction assessment that accompanies approval has not been completed. Theoretical considerations include caution in individuals with active malignancies (despite the absence of demonstrated IGF-1 elevation, any compound interacting with adipose tissue signaling pathways warrants caution in oncology contexts), pregnant or breastfeeding individuals (no safety data exists for these populations), and individuals with severe metabolic conditions where the lipolytic activity might have unpredictable effects. For any research application, consultation with appropriate medical and regulatory expertise is essential. Our AI peptide coach can help answer general informational questions about AOD-9604 research contexts.
You’ll see both “HGH fragment 176-191” and “HGH fragment 177-191” used in discussions of AOD-9604, and the distinction matters. The numbering difference reflects the added N-terminal tyrosine residue in AOD-9604. Some vendors and researchers use “176-191” loosely to refer to the same compound, but strictly speaking, AOD-9604 (the Monash University developed compound with TGA food supplement classification) is Tyr-hGH 177-191, meaning it has that tyrosine addition. The structural distinction affects stability and potency. When reading research or evaluating sources, paying attention to which exact sequence is being discussed is worth the effort.
This is an important nuance. The Phase III trial did not demonstrate weight loss of sufficient magnitude to meet the regulatory threshold for approvability — it was an efficacy failure, not a safety failure. The compound produced statistically significant fat loss compared to placebo, but the absolute amount of weight lost was not large enough for regulators to consider the benefit sufficient relative to the cost and inconvenience of treatment. This is actually a common fate for obesity drugs, where the bar is high and effect sizes are often modest. The safety profile was not the limiting factor. This distinction matters because it means the compound’s safety data is genuinely clean, not the result of the trial being stopped for safety reasons before sufficient data accumulated.
The published research consistently finds that AOD-9604 does not significantly affect lean mass in either direction. It doesn’t build muscle (it lacks the IGF-1-stimulating, anabolic activity of whole GH), and it doesn’t cause muscle wasting at studied doses. Body composition data from clinical trials showed fat mass reduction with lean mass preservation. This is considered a methodologically clean profile for metabolic research where researchers want to attribute body composition changes specifically to fat loss rather than disentangle multiple tissue changes simultaneously.
Research has explored oral delivery and found that AOD-9604 has more oral bioavailability than most peptides of its size, though significantly less than subcutaneous injection. Clinical trials used both routes, with oral arms requiring substantially higher nominal doses to produce measurable effects. The Australian TGA’s food supplement classification applies specifically to oral use, and the research supporting that classification examined oral bioavailability and safety. Whether oral bioavailability is sufficient for a given research application depends on the specific endpoints and methods being used.
AOD-9604 operates through a fundamentally different mechanism than GHRH analogs like CJC-1295 or GH secretagogues like ipamorelin. Those compounds work by stimulating the pituitary to release more endogenous GH, which then elevates IGF-1 and produces a broad spectrum of GH effects including anabolism and lipolysis together. AOD-9604 bypasses the GH axis entirely and acts more directly at the adipocyte level to stimulate lipolysis. It’s a mechanistically cleaner tool for isolating fat mobilization research from the broader GH/IGF-1 system. For a comparative overview of these compound classes, our peptide database has detailed individual profiles.
The cartilage research emerged somewhat independently from the metabolic focus of the original development program. The hypothesis that GH-related fragments might support connective tissue repair is mechanistically grounded — GH and IGF-1 are known regulators of chondrocyte activity, and fragments with partial biological activity might retain some tissue-supportive properties. The published data in this area is preliminary and largely preclinical, but it has been sufficient to attract research investment and investigation. This application may ultimately prove more or less significant than the metabolic application depending on how the research develops.
Regulatory status varies by country and jurisdiction. In Australia, AOD-9604 has been approved as a food supplement ingredient by the TGA, which is a specific regulatory pathway distinct from pharmaceutical approval. In the United States, the FDA does not recognize AOD-9604 as an approved drug or food ingredient, and it falls into a gray regulatory category common to many research peptides. Many countries have no specific regulatory position on the compound. Research use in a licensed laboratory context differs from consumer supplementation use under most regulatory frameworks. Anyone considering AOD-9604 should verify current legal status in their jurisdiction and ensure compliance with applicable regulations.
Our peptide dosing calculators include tools for working through reconstitution math, concentration calculations, and volume calculations for research peptides including AOD-9604. The AI peptide coach is also available for general informational questions about published research protocols and study designs.
Disclaimer: This information is for research and educational purposes only. It is not medical advice. Consult a qualified healthcare professional before using any peptide.