Mazdutide: What the science really says about the two-hormone weight-loss shot

Mazdutide is a once-weekly injection that copies two natural hormones at once: GLP-1, the hormone behind Wegovy (semaglutide), and glucagon. Developed by Eli Lilly and approved in China in 2025, it has produced impressive weight loss and striking drops in liver fat in large trials. Here's what the research shows, what's known about safety, and where it stands in the U.S.

Peptide Advocate · Research explainer · Updated October 2026

What is mazdutide?

Mazdutide was created by Eli Lilly, the maker of Zepbound (tirzepatide), and licensed to China's Innovent Biologics, which developed it in China. Lilly keeps the rights everywhere else.⁵ It's modeled on oxyntomodulin, a natural gut hormone that acts on two receptors at once.²

• GLP-1 helps the body release insulin, lowers blood sugar and makes you feel full sooner, just like Wegovy (semaglutide).
• Glucagon is better known for raising blood sugar, but in this combination it's used to increase the energy the body burns and to help clear fat from the liver.²

In June 2025, China approved mazdutide for chronic weight management, the first drug of its type approved anywhere, according to Innovent. It's sold in China as Xinermei.^3,5

Why researchers are excited

The GLP-1 drugs already work well. Adding glucagon aims to do a few things they can't do as strongly on their own:

• Substantial weight loss. In the GLORY-1 trial, people lost an average of 11% to 14% of their weight over 48 weeks, depending on dose, compared with a slight gain on placebo.^1,2
• Even more at higher doses. A newer, higher dose produced 16.7% average weight loss at 60 weeks, and a U.S. trial saw up to 18.1% at its highest dose.^6,7
• Melting liver fat. In people with a lot of liver fat, it cut that fat by up to 80%, a promising sign for fatty liver disease, which affects many people with obesity.²
• Healthier numbers overall. It also lowered blood pressure, cholesterol, triglycerides and uric acid.²

What about people?

Mazdutide has one of the strongest evidence bases of any peptide in our series. Most trials were run in China, but Lilly has now reported results from a U.S. trial too.

Is mazdutide safe?

Mazdutide's side effects look much like those of other GLP-1 drugs, with a couple of things to watch because of the glucagon component.^2,6

• Stomach side effects are the main issue. Nausea, diarrhea and vomiting were the most common, mostly mild to moderate.² They were more frequent at the highest dose: in GLORY-2, about half of people on that dose had vomiting and nearly half had nausea at some point, mainly while the dose was being increased.⁶
• Some people stop. In the U.S. trial, 20% of people on the highest dose stopped treatment, mostly because of stomach problems.⁷
• Heart rate. Heart rate rose slightly, by about 2.6 beats per minute on average, with a larger temporary rise while the dose was being increased.^2,6 Researchers haven't seen signs of increased heart risk, but long-term heart outcome studies haven't been done.²
• Class warnings likely apply. Approved GLP-1 drugs carry warnings about pancreatitis, gallbladder problems and, based on rodent studies, a type of thyroid tumor. Mazdutide's long-term safety is still being studied.

Athletes: Mazdutide's anti-doping status hasn't been widely addressed. Check with your anti-doping authority before using any new medicine.

Where mazdutide stands with the FDA

Mazdutide isn't FDA-approved, and as of spring 2026 no U.S. application had been filed.⁸ But because it's Lilly's drug outside China, it has a clearer path to the U.S. than most foreign peptides. Lilly ran a U.S. phase 2 trial and published the results in August 2026. It hasn't announced U.S. phase 3 plans, and is still working out the best long-term dose.^5,7

How mazdutide's status has changed

1. 2019Innovent licenses mazdutide from Eli Lilly for development in China⁵
2. May 2025GLORY-1 phase 3 results published in the New England Journal of Medicine²
3. June 27, 2025China approves it for chronic weight management, the first dual glucagon/GLP-1 drug approved anywhere³
4. September 19, 2025China approves it for blood-sugar control in type 2 diabetes⁴
5. October 2025Beats semaglutide on combined blood-sugar and weight goals in the DREAMS-3 trial⁵
6. June 2026Higher-dose GLORY-2 results published in JAMA⁶
7. August 2026Lilly publishes U.S. phase 2 results⁷
8. NextWatch for U.S. phase 3 plans from Lilly; no FDA filing yet^7,8

What this means for you: If you're in the U.S., mazdutide isn't an option today, but approved GLP-1 medicines are. Given Lilly's involvement, mazdutide is one of the more likely new peptides to reach U.S. patients eventually. We'll update this article as that unfolds.

If you're curious about mazdutide

• Talk to your doctor about approved options. Wegovy (semaglutide) and Zepbound (tirzepatide) are FDA-approved for weight management.
• Have fatty liver disease? Ask about approved treatments and whether a clinical trial might be a fit.
• Skip online "research" versions. They aren't regulated, and dose, purity and sterility are unknown.
• Protect your muscle. Eating enough protein and doing strength training help during any weight loss.
• Look for clinical trials if you're interested in new treatments, the safe way to try them.

The bottom line

Mazdutide is one of the most promising new weight-loss drugs in the world. It pairs GLP-1 with glucagon to deliver strong weight loss and dramatic cuts in liver fat, and it's backed by large trials, two approvals in China, a win over semaglutide in diabetes and a U.S. trial from Lilly. The trade-offs are familiar: stomach side effects, especially at higher doses, a small rise in heart rate, and long-term safety that's still being studied. For Americans, it's not available yet, but it's a name worth remembering.

References

1. Ji L, Jiang H, et al. GLORY-1: phase 3 trial of mazdutide in Chinese adults with overweight or obesity. N Engl J Med. 2025. doi.org
2. Innovent Biologics. Phase 3 clinical study of mazdutide in Chinese adults with overweight or obesity (GLORY-1) published in the New England Journal of Medicine; May 25, 2025. biospace.com
3. Innovent Biologics. Mazdutide, first dual GCG/GLP-1 receptor agonist, received approval from China's NMPA for chronic weight management; June 27, 2025. biospace.com
4. Innovent Biologics. Mazdutide received approval from China's NMPA for glycemic control in adults with type 2 diabetes; September 19, 2025. biospace.com
5. TechTarget. Innovent, Lilly's mazdutide outdoes Novo's semaglutide in phase 3 trial; October 27, 2025. techtarget.com
6. Drug Topics. Mazdutide shows weight reductions for patients with obesity (GLORY-2; Gao L, et al. JAMA, 2026); June 8, 2026. drugtopics.com
7. Pharmacally. Mazdutide produces up to 18.1% weight loss in U.S. phase 2 obesity trial (Lancet Diabetes Endocrinol, August 2026); August 24, 2026. pharmacally.com
8. FormBlends. Mazdutide FDA approval timeline; updated April 27, 2026. formblends.com
9. Pharmaceutical Technology. FDA cracks down on black market peptide trade; September 2, 2026. pharmaceutical-technology.com

This article is for general education and is not medical advice. Mazdutide is not approved by the FDA to diagnose, treat, cure or prevent any condition, and this article does not recommend using it or provide dosing information. Talk with a licensed healthcare provider before starting any new treatment. Regulatory information is current as of October 16, 2026 and is changing quickly. Charts and illustrations are original works by Peptide Advocate.