Does AOD-9604 Actually Burn Fat? What Happened in the 502-Person Trial

Five hundred two people took oral AOD-9604 or placebo for 24 weeks, and the drug did not beat placebo on the weight-loss endpoint the trial was built to test.¹ No regulator has approved it for human use, and the FDA review of it concluded that the evidence does not support its effectiveness.¹ The company that ran it said the results did not support commercial viability.¹ An FDA advisory committee later voted 12 to 0 against putting the compound on the compounding list, and the minutes record no discussion at all.²

None of those trials was ever registered or published as a paper. The best public account of them is a regulatory review, not a journal.

Does AOD-9604 burn fat?

AOD-9604 did not burn fat in the people it was tested on. FDA's own evaluation of the compound states that "In most of the studies we identified, AOD-9604 failed to show benefit for weight reduction when compared to placebo," and concludes that "there is a lack of evidence to support the effectiveness of AOD-9604 (free base) and AOD-9604 acetate."¹

The story behind the interest is a rodent story. AOD-9604 is a fragment of human growth hormone, the 176 to 191 region, isolated because that stretch appeared to carry lipolytic activity without the growth-promoting part. Our guide to the growth hormone peptides covers where it sits among the others.

FDA does not treat the mechanism as settled. Its review states that "The molecular target(s) and the mechanism(s) of action underlying the pharmacological effects of AOD-9604 remain unknown," and adds that this makes the biological plausibility of the reported effects hard to assess.¹ Twenty years of human dosing has produced no weight-loss benefit anybody could publish and no identified target.

What was the 502-person trial, and what did it find?

The 502-person trial was a randomized, double-blind, placebo-controlled study in adults with obesity, and it found nothing. The review identifies it by the internal code METAOD006 and describes it as "An R, DB, PC study in 502 males and females with obesity (no ages specified)."¹ The same review records 536 enrolled for the trial it calls OPTIONS.¹

Participants took oral AOD-9604 at 0.25, 0.5 or 1 mg once daily, or placebo, for 24 weeks.¹ The primary endpoint was "statistically significant weight loss after 12 weeks of treatment for any one of three daily" doses.¹ Three chances to hit, measured at the halfway point of a 24-week study, is a generous design.

Two participant figures appear for what seems to be one trial. The briefing document gives 536 enrolled under the name OPTIONS and 502 in the study population under the internal code METAOD006.¹ Nothing in the review reconciles them, and the gap is the ordinary distance between enrolled and analyzed. This page uses 502, because 502 is the figure attached to the study summary FDA actually read.

The summary states that "there was not a significant difference in the primary endpoint of weight loss between placebo and AOD-9604."¹

Behind that result sits the company's own assessment, quoted in the same document as saying "the Phase 2B trial results for its drug, AOD9604, do not support the commercial viability of" the program.¹ A sponsor walking away from its own lead asset is the strongest form of negative result available, because nobody had an incentive to reach it.

Figure 3 of the review carries the trial's weight data as an image, and the numbers behind it are not in the document text. No per-arm weight change from that trial is quoted on this page for that reason.

What did the animal studies show?

The animal studies showed weight loss in obese rodents, and the effect sizes were large. The review summarizes a 21-day oral gavage study in which "adult obese male and female Zucker rats were treated with AOD-9604" and reports that "Obese rats treated with AOD-9604 or hGH gained approximately 50% less body weight" than controls, with "significantly higher lipolytic activity in adipose tissue."¹ A 14-day study in obese ob/ob mice found that treated animals "gained ~5-10% less body weight than vehicle-treated mice", alongside "reduced white and brown adipose tissue" and "increased in-vivo fat oxidation."¹

One experiment pinned down a dependency. In mice lacking the beta-3 adrenergic receptor, AOD-9604 "had no effect on body weight gain, size of epididymal white and brown adipose tissues", while in wild-type obese mice it "increased expression of β3 adrenergic receptors."¹ Reviewers draw the conclusion that "the lipolytic effects of AOD-9604 depend, at least in part, on intact β3 adrenergic receptor signaling."¹

Two methodological notes sit underneath all of it. FDA records that "none of the studies assessed dose-response relationships for AOD-9604" and that "statistical treatment of the data in all studies was not corrected for multiple comparisons."¹ No lean-animal comparison appears anywhere in the review.

Why were the doses so much smaller than in the early studies?

Oral doses dropped roughly fiftyfold between the first studies and the big one. An early oral trial in 16 men with obesity used 9, 27 and 54 mg once weekly for 4 weeks.¹ By the 502-person trial the doses were 0.25, 0.5 and 1 mg once daily.¹

One finding sits between them. A 300-patient study reported by Herd and colleagues in 2005 found that "Weight loss over 12 weeks was greater in the response to all doses of AOD-9604 than placebo," and that "The largest effect occurred in the 1 mg dose and was 'significant' for females."¹

So the dose that looked best in a 300-person study became the top dose in a 502-person study, and the effect did not survive. Neither document states the sponsor's reasoning for the change, and that sequence is the ordinary shape of a signal that was noise.

What did the earlier trials show?

The earlier trials were small, short and mostly negative. Three studies attributed to Wilding in 2004 are summarized in the review. First came a study giving "23 adults with obesity" single doses of intravenous AOD-9604 at 25, 50 or 100 mcg/kg or placebo, once weekly for 4 weeks.¹ The second, in "16 men with obesity", used oral doses once weekly for 4 weeks and found "there was no statistically significant weight loss compared with placebo."¹

Marketing material likes the third. In that study, "Average weight loss over 1 week at the 10-mg dose was reported to be 1 kg compared with 0.6 kg in the placebo group."¹

A 0.4 kg difference over one week is the high-water mark of the human record for this compound.

Where does the 1 kg figure in the marketing come from?

The 1 kg figure comes from that one-week result, usually quoted without its comparator. Pages selling AOD-9604 cite a kilogram of weight loss and leave out the 0.6 kg the placebo group lost over the same week, turning a 0.4 kg difference into a 1 kg claim.¹

What is missing matters as much as what was reported. Nowhere does the review state how many people were in that study, so the figure arrives with no sample size, no p value and no confidence interval. A one-week weight difference of 400 grams in an unstated number of people is compatible with almost anything, including nothing.

Our guide to what a research-use-only label actually means covers the framework these products are sold under. Here the figure problem is simpler than the legal one: a number that is accurate in isolation and misleading in use.

Why is none of this in a journal?

Because the trials were never registered and never written up for a journal. The review states plainly that "A search of clinicaltrials.gov did not list any studies on AOD-9604."¹ What exists instead is a set of sponsor study summaries, identified by internal codes that run METAOD0003, METAOD004, METAOD005 and METAOD006, plus a conference abstract from 2005, all of them read and described by FDA reviewers.¹

Reviewers were not satisfied with what they received. They noted that the study summaries lacked detail and recorded "concerns about the reports of various cancers."¹

That gap is why a compound with six human studies can be described as having no clinical trial publications. Those studies happened. The literature never received them.

What does FDA say about the evidence?

FDA's assessment of the evidence comes down to two sentences. The review concludes that "there is a lack of evidence to support the effectiveness of AOD-9604 (free base) and AOD-9604 acetate," and that "In most of the studies we identified, AOD-9604 failed to show benefit for weight reduction when compared to placebo."¹

Both appear in a briefing document prepared for an advisory committee instead of a rejection letter, because AOD-9604 was never submitted for approval anywhere. FDA was assessing whether pharmacies should be allowed to compound with it. That is a lower bar than approval, and it did not clear that one either.

Four review units signed it, so this is not one reviewer's opinion. Staff from the Office of Pharmaceutical Quality, the Office of Compliance, the Office of New Drugs and the Pharmacy Compounding Review Team signed the memorandum, dated 11/5/2024.¹ Quality, compliance and clinical review units reached the same conclusion about the same evidence.

What did the advisory committee decide?

The advisory committee decided against it, unanimously. At its meeting of December 4, 2024, the question put was "Should AOD-9604 (free base) and AOD-9604 acetate be placed on the list?" Twelve voted no, none voted yes, and nobody abstained.²

The minutes then record one line about the deliberation: "There was no committee discussion regarding this question."²

One procedural vote came first. The committee agreed 12 to 0, with no abstentions, to consider AOD-9604 free base and AOD-9604 acetate as a single group rather than separately.² So the twelve members who could not find anything to debate about the substance did agree unanimously on how to handle it. Approval of those minutes followed on February 21, 2025.²

For comparison, the same committee recommended BPC-157 and TB-500 for the compounding list in July 2026 by 8 votes to 6 on each, as our comparison of BPC-157 and TB-500 reports. A split committee argued about those two. On AOD-9604 twelve members agreed without debate.

Is AOD-9604 on the new HHS compounding list?

No, AOD-9604 is not on the HHS compounding list. HHS published that enforcement discretion policy on October 30, 2026, listing six peptides in Appendix A: BPC-157, Epitalon, KPV, MOTS-c, Semax and TB-500.³ AOD-9604 is not among them.

Our coverage of what that HHS policy actually allows sets out the ten conditions attached to the six that are listed. A peptide absent from that appendix sits where it sat before, and AOD-9604 has the additional history of a unanimous vote against it.

Its position moved once more in between. A separate FDA list now places AOD-9604 not in category 2 but in a table of "bulk drug substances previously in category 2 of the interim policies" that "were withdrawn by the nominators."⁴ That page carries a last-updated date of April 22, 2026, the same date the HHS policy records for peptides leaving category 2.³⁴

Every step ran in one direction. Reviewed in 2024, voted down 12 to 0, nomination withdrawn by whoever had nominated it, and absent from the access list that arrived in October 2026.

What does the FDA safety-risk list say about it?

The safety-risk list names three specific concerns, none of them about weight. Its page on bulk substances that may present significant safety risks states that "Compounded drugs containing AOD-9604 may pose significant risk for immunogenicity for certain routes of administration" and "may have complexities with regard to peptide-related impurities and API characterization."⁴

Immunogenicity is the first. A peptide fragment injected repeatedly can provoke an immune response, and the risk is route-dependent, so that sentence names routes instead of the molecule alone. Peptide-related impurities are the second, meaning the truncated and modified sequences that synthesis leaves behind. API characterization is the third: establishing that the material in the vial is the stated molecule at all. Our guide to reading a peptide COA covers what a certificate does and does not establish on that last point.

The same entry adds that "FDA has also identified serious adverse events that may be associated with AOD-9604, though causality is not clear."⁴

What were the safety findings?

Safety findings read mild in the summaries and thin in the reporting. Across the intravenous studies the most common adverse events were headache, fatigue, unspecified hypoglycemia and dizziness, with chest tightness and euphoria assessed as possibly related to treatment.¹ One oral study logged 97 adverse events across 17 subjects, with diarrhea possibly related.¹ Another recorded "A total of 36 subjects reported 207 AEs, but AEs were not listed or quantified."¹

For the 502-person trial, the sponsor's summary states there were "no AEs that were deemed to be definitely related to the study treatment."¹

Counting events without naming them is not a safety dataset. Reviewers said as much about the level of detail they were given.¹

Animal toxicology produced three signals of its own. A change in rat osteocalcin "can be interpreted as a clinically relevant nonclinical safety signal."¹ In monkeys, the review says "the possibility cannot be ruled out that AOD9604-induced cytoplasmic vacuolation of hepatocytes" occurred.¹ Genotoxicity results were equivocal, and the review says the positive signals "cannot be regarded as biologically insignificant."¹ Its overall verdict is that the "nonclinical studies were too limited in scope to inform safety considerations."¹

One absence is specific and practical. FDA states it "did not identify repeat-dose toxicity studies of subcutaneously or transdermally delivered" AOD-9604.¹ Subcutaneous injection is the route people actually use.

Five subjects in one oral study had serious adverse events, and the list included several cancers. The principal investigator considered them unrelated to the study medication, and the study authors wrote that "therefore, a dose effect can be excluded."¹

Reviewers did not accept that reasoning at face value. Their write-up records "concerns about the reports of various cancers" alongside the observation that the summaries lacked detail.¹

Nothing here establishes that AOD-9604 causes cancer, and nothing here rules it out. A handful of events in a small study, declared unrelated by the people running it and queried by the regulator reading it, is an open question rather than a finding in either direction. Nobody would look twice if the parent molecule were not a growth hormone fragment.

Is AOD-9604 approved anywhere?

AOD-9604 is not approved anywhere for human use. It has never been approved as a drug in any jurisdiction, it is sold labeled for laboratory research, and the World Anti-Doping Agency prohibits it at all times, in and out of competition.

FDA puts the knowledge gap more bluntly than the approval status does. Its safety-risk page states that "FDA has identified no, or only limited, safety-related information" for AOD-9604 and that "Therefore, the agency lacks sufficient information to know whether the drug would cause harm when administered to humans."⁴

That is a different claim from saying a compound is dangerous. Twenty years after the first human dosing, the regulator's position is that it does not know, and the party best placed to resolve it stopped trying.

Our AOD-9604 compound page carries the dosing, pricing and storage detail along with the regulatory entries. The human trial record is what this page documents.

What has not been measured?

A human half-life has never been measured. Six studies dosed people with this compound and none of them published a human pharmacokinetic figure, so the dosing intervals people use are unanchored to any measured clearance. Our peptide half-life chart lists AOD-9604 with an animal figure and marks it as animal data only. The same gap shows from the other direction.

Body composition is the second gap. Weight is what the trials measured, and a lipolytic fragment is interesting mainly if it changes fat mass instead of scale weight. Our guide to peptide half-life and why it differs from duration of effect covers why the first gap matters more than it sounds.

No trial can close the third one now. The sponsor stopped development, nothing is registered, and no current study is recruiting, so the evidence base for AOD-9604 is closed at six unpublished studies and a 12 to 0 vote.

Why does our own compound page say no clinical trial is on record?

Because two true things on that page look like a contradiction, and one of them is worded wrongly. Our AOD-9604 compound page states in its body that around 900 people took part in six human trials, including a 502-person phase 2b that missed its primary endpoint. Its research index reports "0 clinical trial publications" and gives the furthest stage reached as "No clinical trial on record."

Publication counts are right. No paper exists, nothing is registered, and FDA's own search of clinicaltrials.gov returned nothing.¹ The stage line is wrong. AOD-9604 reached Phase 2b, and a 502-person randomized placebo-controlled trial is on record in an FDA briefing document even though it is absent from the literature. That line is being corrected to name the stage and the reason it is unpublished.

Common questions

Does AOD-9604 burn fat?

What happened in the 502-person AOD-9604 trial?

Is AOD-9604 FDA approved?

Did the FDA advisory committee vote on AOD-9604?

Is AOD-9604 on the 2026 HHS compounding list?

Where does the 1 kg weight loss claim come from?

Why is there no AOD-9604 paper to read?

How many people have taken AOD-9604 in trials?

Did any AOD-9604 trial show weight loss?

Were there safety problems?

Did AOD-9604 work in animals?

Is the mechanism of AOD-9604 known?

Has AOD-9604 been tested for safety by injection?

Is AOD-9604 banned in sport?

Is AOD-9604 the same as HGH Fragment 176-191?

Is a human half-life known?

Could a new trial change this?

Sources

Sources

1. U.S. Food and Drug Administration. Evaluation of AOD-9604-related Bulk Drug Substances (AOD-9604 (free base) and AOD-9604 acetate) for Inclusion on the 503A Bulk Drug Substances List. FDA Briefing Document prepared for the Pharmacy Compounding Advisory Committee meeting of December 4, 2024; review memorandum dated 11/5/2024, from the Office of Pharmaceutical Quality, the Office of Compliance and the Office of New Drugs. Read at source at fda.gov, in two windows across a document of roughly 105,500 characters. Quoted for every trial description, participant count, dose, duration, endpoint, result, adverse event figure and FDA conclusion on this page. Figure 3 carries the 502-person trial's weight data as an image whose underlying numbers are not in the document text, so no per-arm weight change from that trial is quoted. ↩1 ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13 ↩14 ↩15 ↩16 ↩17 ↩18 ↩19 ↩20 ↩21 ↩22 ↩23 ↩24 ↩25 ↩26 ↩27 ↩28 ↩29 ↩30 ↩31 ↩32 ↩33 ↩34 ↩35 ↩36 ↩37 ↩38 ↩39 ↩40 ↩41 ↩42
2. U.S. Food and Drug Administration. Final Summary Minutes of the Pharmacy Compounding Advisory Committee Meeting, December 4, 2024; minutes approved February 21, 2025. Read at source at fda.gov. Quoted for the question put to the committee, the 0 yes, 12 no, 0 abstaining vote on AOD-9604 free base and AOD-9604 acetate, and the recorded absence of committee discussion. ↩1 ↩2 ↩3 ↩4 ↩5
4. U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks. Page last updated 04/22/2026. Read at source at fda.gov. AOD-9604 appears not in the category 2 table but in the table of substances "previously in category 2 of the interim policies" that "were withdrawn by the nominators." Quoted for the immunogenicity, peptide-related impurity and API characterization concerns, for the statements about limited safety information and insufficient information to know whether the drug would cause harm, and for the serious adverse event wording. ↩1 ↩2 ↩3 ↩4 ↩5
3. U.S. Department of Health and Human Services. HHS Enforcement Discretion Policy Regarding 503A Compounding Using Certain Peptide Bulk Drug Substances, Appendix A. Read at source at hhs.gov on 30 October 2026. The accompanying Federal Register notice of availability is document number 2026-22192, published 30 October 2026. Cited only for the six-peptide contents of Appendix A. AOD-9604 is not among them. ↩1 ↩2