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AOD-9604

A modified C-terminal fragment of growth hormone marketed for fat loss without GH's effects on blood sugar or IGF-1, which is true - but the human weight-loss data is essentially negative.

Also known as hGH fragment 177-191 with N-terminal tyrosine, Anti-Obesity Drug 9604, Tyr-hGH(177-191), AOD9604

Human RCT — Randomised controlled trials in humans, but not an approved product for this use.

Rodent data on lipolysis is solid and reproducible, but the pivotal 12-week human obesity trial found no significant weight loss versus placebo, which is why development stopped. It has an unusually clean safety record and generally recognised as safe status in the US as a food ingredient in some contexts, so the honest summary is: safe, well tolerated, and probably not effective at the doses people inject.

How it works

AOD-9604 is hGH residues 177 to 191 with an added N-terminal tyrosine for stability. In rodent adipocytes it increases beta-3 adrenergic receptor expression and stimulates lipolysis while inhibiting lipogenic enzymes, and it does this without measurable GH-receptor binding, so IGF-1 and glucose tolerance are unchanged - which was the whole selling point. In beta-3 receptor knockout mice the lipolytic effect disappears, implicating that pathway directly. Human results have not matched: a 12-week phase 2b obesity trial found no significant weight loss versus placebo. A separate line of work on intra-articular AOD-9604 for cartilage repair produced some interesting animal data but nothing conclusive in humans.

Targets: Adipocyte beta-3 adrenergic receptor expression, Hormone-sensitive lipase, Lipogenic enzymes

Dosing

ProtocolDoseFrequencyRoute
Common grey-market protocolFasted in the morning, ideally before cardio.300 mcg – 500 mcgonce dailysubcutaneous
Oral trial doseFasted.—once dailyoral
  • · 300 mcg daily is the near-universal figure quoted, and it traces back to marketing rather than to a dose-finding study.
  • · The phase 2 obesity programme used oral doses in the 1 mg/kg range - roughly 20 to 60 mg daily - which is two orders of magnitude above what grey-market injectable protocols use. It still did not beat placebo.

Cycling

Typically run for 12 weeks alongside a caloric deficit. Given the negative human trial, the honest framing is that the cycle length matters less than whether the compound works at all.

Work out your exact syringe units →

Pharmacology

Half-life
Short - well under an hour subcutaneously; oral bioavailability is poor and the exact value is not well characterised.
Onset
No reliable acute effect. Claimed body-composition changes are described over 8 to 12 weeks, but the human trial data does not support them.
Routes
subcutaneous, oral, topical
Molecule
Modified synthetic hGH C-terminal fragment (Tyr + residues 177-191)
Sequence length
16 amino acids
Molecular weight
1815.9 Da

Handling

Diluent
Bacteriostatic water
Typical mix
2 mL
Vial sizes
2, 5 mg
Lyophilised
Refrigerate; freeze for long-term.
Reconstituted
Refrigerated, use within about 30 days.
Light sensitive
Yes — keep it out of the light

Mixing

A 5 mg vial in 2 mL gives 2500 mcg/mL; 12 units on a U-100 syringe is 300 mcg.

Side effects

  • commonInjection-site reaction
  • uncommonHeadache
  • uncommonNausea— More common with the high oral doses used in trials.
  • rareDizziness

Do not use if

  • Pregnancy and breastfeeding, where there is no data.
  • Known hypersensitivity to the peptide.

Combining it

  • redundanthgh-fragment-176-191 — AOD-9604 is essentially the stabilised version of the same fragment. Running both makes no sense.
  • cautionsemaglutide — Sometimes stacked for fat loss; the GLP-1 is doing all the work.
  • synergyBeta-3 agonists — Mechanistically plausible given the beta-3 pathway, but untested in humans.

What to monitor

  • · Body composition and waist circumference, since this compound's whole claim is regional fat loss.
  • · No routine bloodwork is indicated - it does not move IGF-1 or glucose, which is both its selling point and, arguably, a hint about its potency.

Legal status

Not an approved drug. It has been the subject of GRAS notifications as a supplement ingredient in the US, which is not a claim of efficacy. Prohibited in sport under WADA S2.

References

  • Heffernan et al. 2001, effects of hGH and its lipolytic fragment AOD-9604 in obese and beta-3 knockout mice (preclinical)
  • Metabolic Pharmaceuticals phase 2b oral AOD-9604 obesity trial, which failed its primary weight-loss endpoint (trial)

Mechanism in depth

The sequence here was derived directly from the verified human somatotropin sequence (UniProt P01241): the mature 191-residue chain ends ...MDKVETFLRIVQCRSVEGSCGF, so residues 177 to 191 are LRIVQCRSVEGSCGF and adding the N-terminal tyrosine gives YLRIVQCRSVEGSCGF. That single tyrosine is worth dwelling on, because it produces one of the more useful clarifications in this whole class: the sequence that vendors sell as 'HGH Fragment 176-191' is usually this one, and this one is AOD-9604. The true hGH(176-191) begins with phenylalanine, not tyrosine. Mechanistically AOD-9604 does not act at the GH receptor at all - that is the selling point and it is genuine. In rodent adipocytes it increases beta-3 adrenergic receptor expression, stimulates lipolysis and inhibits lipogenic enzymes, and in beta-3 knockout mice the lipolytic effect disappears, which is about as clean a mechanistic demonstration as preclinical work gets. Because it never engages the GH receptor, IGF-1 and glucose tolerance are unchanged. The problem is that all of this is true and it still did not work in people. The 12-week phase 2b obesity programme used oral doses around 1 mg/kg - roughly 20 to 60 mg daily, two orders of magnitude above what grey-market injectable protocols deliver - and failed its primary weight-loss endpoint. There is a plausible species explanation: mouse adipocytes are much more beta-3-dependent than human adipocytes, where beta-1 and beta-2 dominate lipolysis. If the mechanism runs through beta-3, human translation was always going to be the hard part.

What usually goes wrong

The failure is quiet: nothing happens, and because AOD-9604 has no perceptible acute effect and moves no blood marker, there is no feedback to tell you. People run it for twelve weeks alongside a deficit, lose weight from the deficit, and attribute it to the peptide. The dose discrepancy is the specific thing worth knowing: the human trial used roughly 20 to 60 mg orally per day and still failed, while the standard grey-market protocol is 300 mcg subcutaneously - a hundred-fold lower total dose by a different route. Whatever the injectable route buys in bioavailability, it does not plausibly close a hundred-fold gap. The 300 mcg figure traces to marketing rather than to any dose-finding study. The second issue is the GRAS framing: AOD-9604 has been the subject of generally-recognised-as-safe notifications as a supplement ingredient in the US, which is a statement about safety, not efficacy, and it gets quoted as if it were an endorsement. The third is joint and cartilage marketing, which rests on a rabbit study.

Bloodwork worth running

MarkerWhenWhy it matters
Waist circumference and body compositionBaseline and 12 weeks, fasted, same time of day.The entire claim for this compound is regional fat loss, so the measurement that matters is a tape measure and a DEXA scan, not a blood test.Act if: No change at 12 weeks alongside a controlled deficit means it is not contributing. Given the trial result, that should be the expected outcome rather than a surprise.
IGF-1Baseline and 12 weeks, only if you want to verify product identity.Not to monitor for harm, but as a mechanism check. AOD-9604 should not move IGF-1 at all; if yours rises, you have been sold something else.Act if: Any IGF-1 rise on AOD-9604 means the vial contains something with GH-axis activity.
Fasting glucoseBaseline only, unless something changes.Included for completeness rather than concern. The absence of a glucose effect is a documented and reproducible property.Act if: No expected action.

Pharmacokinetics

Crosses blood-brain barrier
no
Metabolism
Peptidase hydrolysis. Cox et al. published in vitro metabolism data in the anti-doping literature, identifying degradation products used for detection.
Elimination
Not characterised.

Receptor targets

  • Adipocyte beta-3 adrenergic receptor (expression, not direct binding) — Not a direct ligand. Increases beta-3 receptor expression in rodent adipocytes; the lipolytic effect is abolished in beta-3 knockout mice.

    Increased lipolysis and fat oxidation in rodents. Human beta-3 receptors are far less important for adipose lipolysis than rodent ones, which is the leading explanation for the failed human trial.

  • Hormone-sensitive lipase and lipogenic enzymes — Not applicable

    Increased lipolysis, decreased lipogenesis in rodent adipose tissue.

  • Growth hormone receptor — No measurable binding

    Explicitly absent. IGF-1, glucose tolerance and insulin sensitivity are unchanged - the entire design rationale, and arguably a hint about why it does so little.

  • Articular cartilage (intra-articular use) — Not characterised

    Kwon and Park reported effects of intra-articular AOD-9604 with and without hyaluronic acid in a rabbit osteoarthritis model. Interesting, and rabbit.

Trials

  • Metabolic Pharmaceuticals phase 2b oral AOD-9604 obesity programme 2b · 12 weeks

    Weight loss versus placebo. The trial did not achieve a significant weight-loss difference, and development stopped. This trial is widely referenced and is the reason nobody should describe AOD-9604 as a proven fat-loss agent, but it was not verified against a primary publication in this session.

  • Kwon and Park, intra-articular AOD-9604 with or without hyaluronic acid in a rabbit osteoarthritis model preclinical · 2015

    Cartilage and joint outcomes in rabbit osteoarthritis. The origin of the joint and cartilage claims, and it is a rabbit study.

What to expect, and when

There is no reliable acute effect and nothing to feel. Vendor material describes body-composition changes over eight to twelve weeks; the controlled human trial over twelve weeks found no significant weight loss versus placebo, so the honest onset timeline is that there is no established onset. If you use it, the only meaningful assessment point is a body composition measurement at twelve weeks against a matched period without it.

Stacking and comparisons

There is no stack in which AOD-9604 is the active ingredient. Paired with semaglutide or tirzepatide for fat loss, the GLP-1 is doing all of the work and AOD-9604 is along for the ride. Paired with HGH fragment 176-191 it is straightforwardly redundant - they are near-identical molecules. Paired with a GH secretagogue it does not conflict, because it does not touch the GH axis, but it also does not add anything demonstrated. The one combination with a mechanistic rationale is with a beta-3 agonist such as mirabegron, given the knockout-mouse data, and that has never been tested in humans. The honest stacking note is that this compound's best documented property is that it is well tolerated and does not interfere with anything.

Against HGH fragment 176-191: AOD-9604 is the stabilised, actually-tested version of the same idea, with human trial data - negative human trial data, but data. If you are going to use one of the two, use this one. Against a GLP-1 agonist for fat loss: not comparable. Semaglutide and tirzepatide have phase 3 weight-loss data measured in double-digit percentages; AOD-9604 has a failed phase 2b. Against tesamorelin: tesamorelin is the compound in this class with a real, imaging-confirmed, regionally selective fat effect and an FDA approval. AOD-9604 is what people buy when they want that outcome without the cost, and it does not deliver it. Against ephedrine, caffeine or a beta-agonist: those at least produce measurable thermogenesis. The one genuine advantage AOD-9604 has over every alternative is its safety record - it is remarkably well tolerated, and if it did anything, that combination would be valuable.

Rough cost

$35–$100/month. Approximate grey-market pricing. A 5 mg vial typically runs 30 to 70 USD, and at 300 mcg daily that is about 9 mg a month. Expensive relative to what the evidence supports. Figures are observed and approximate.

Genuinely uncertain

  • The phase 2b obesity trial is universally referenced but no primary publication or registry entry was verified in this session, so it is recorded as unverified despite being the single most important fact about the compound.
  • No human pharmacokinetic data exists: no half-life, tmax, bioavailability, clearance or volume of distribution for either route.
  • The molecular weights in circulation are inconsistent. Calculated from the verified sequence YLRIVQCRSVEGSCGF, the reduced free acid is approximately 1801 to 1817 Da depending on how the disulfide and terminal chemistry are counted; the Core record's 1815.9 is in that region but the exact figure was not confirmed against a primary reference.
  • Whether the subcutaneous route materially changes exposure relative to the oral doses used in the trial is unknown, and it is the crux of the grey-market case for the compound.
  • The 300 mcg daily protocol has no dose-finding basis of any kind.
  • Human beta-3 adrenergic receptor contribution to adipose lipolysis is much smaller than in rodents, which is a plausible but unproven explanation for the failed translation.
  • The GRAS notification status referenced in the Core record was not independently reverified here.

Papers