This is an editorial discussion of published research. It is not a treatment plan. A clinician I spoke with recently described a patient who lost 22 pounds on tirzepatide but complained that her arms looked thinner than she wanted. She had added AOD-9604 on her own, hoping to hold onto muscle. The question of stacking a GLP-1 agonist with a growth hormone fragment is now common in weight loss clinics, but the evidence is thin.
The Current Regulatory Picture
Tirzepatide is FDA approved for type 2 diabetes and obesity. AOD-9604 is not approved for any human use. The FDA has sent warning letters to compounding pharmacies selling AOD-9604 as a weight loss drug. State pharmacy boards have also taken action.
In 2023, the FDA added tirzepatide to its drug shortage list, which allowed compounding pharmacies to make copies. That shortage ended for some doses in late 2024. AOD-9604 remains in a gray area, often sold as a research chemical.
What the Research Shows
Tirzepatide reduces body weight by about 15 to 20 percent in trials. Most of that loss is fat, but some lean mass is lost too. A 2022 study in the New England Journal of Medicine found lean mass loss of about 10 percent of total weight lost.
AOD-9604 is a modified fragment of human growth hormone. Its maker claimed it could reduce fat without affecting blood sugar. A 2003 trial in Obesity Research showed no significant fat loss versus placebo. The company later abandoned development.
No published trial has tested tirzepatide plus AOD-9604. The idea of stacking them is based on mechanism, not data. This is a 1 of 3 on evidence quality.
Muscle Loss on GLP-1 Drugs
GLP-1 agonists cause rapid weight loss. Some of that is muscle. The rate of lean mass loss is higher than with diet alone. A 2024 review in Diabetes, Obesity and Metabolism noted that up to 40 percent of weight lost can be lean mass in some patients.
Resistance training and higher protein intake can reduce that loss. Adding a peptide like AOD-9604 has not been shown to help. Tesamorelin, a growth hormone releasing hormone analog, is approved for HIV lipodystrophy but not for general obesity. It does not appear to preserve muscle during weight loss.
What Clinicians Are Saying
Several obesity medicine specialists told this reporter they are seeing more patients ask about peptide stacks. Most advise against AOD-9604 because of weak efficacy data. Some prescribe low dose nandrolone or testosterone for muscle preservation, but that is off label and carries risks.
The cost of AOD-9604 is around $48 per vial from some online sellers. A month of tirzepatide at a compounding pharmacy can run $200 to $400. Insurance rarely covers either for weight loss.
Who Is Affected
Patients using tirzepatide for obesity or diabetes are the main group. Bodybuilders and fitness enthusiasts also stack peptides for cutting cycles. Compounding pharmacies face regulatory risk if they market AOD-9604 for weight loss. Physicians who prescribe off label could face board complaints.
What to Watch Next
The FDA is expected to clarify its position on AOD-9604 in 2025. Clinical trials of GLP-1 plus myostatin inhibitors are underway. Those may offer a more evidence based way to preserve muscle. For now, the stack of tirzepatide and AOD-9604 remains an unproven experiment.
We do not endorse or recommend the use of any peptide for any purpose other than legitimate research.