A New Weight Loss Drug Just Showed Remarkable Results in a Major Clinical Trial. Here’s What to Know About Mazdutide

A new obesity drug is getting a lot of attention, and for good reason. In a large clinical trial, people who took mazdutide lost more than 16% of their body weight in about a year. That is a significant number, and scientists say it puts this drug among the most effective weight loss treatments tested so far.

The trial, called GLORY-2, had its results published in the medical journal JAMA. For 60 weeks, 461 Chinese adults with obesity took either a weekly injection of mazdutide or a placebo shot. Everyone in the study also changed their diet and moved their body more.

The numbers from the mazdutide group were hard to ignore. On average, people lost 16.65% of their body weight. Those in the placebo group lost just 1.50%. More than 84 out of every 100 people on mazdutide lost at least 5% of their weight. Nearly 42% lost 20% or more. In the placebo group, only about 3 in 100 people hit that mark.

So how does this drug actually work? Mazdutide copies a natural hormone in the body called oxyntomodulin. This hormone helps control hunger and the way the body burns energy. Most weight loss drugs today, like semaglutide (sold as Wegovy or Ozempic) and tirzepatide (Mounjaro), hit one specific receptor in the body called GLP-1. Mazdutide goes a step further. It hits two receptors at once, both GLP-1 and glucagon. Targeting both pathways at the same time appears to boost the drug’s effect on weight and overall metabolic health.

Beyond weight loss, the drug also improved several heart health markers. People taking mazdutide lost nearly 13 centimeters off their waist, compared to just 2 centimeters in the placebo group. Their blood pressure dropped by about 10 points. Triglyceride levels, a type of fat in the blood, fell by more than 21% in the mazdutide group. The placebo group saw those levels go up. LDL and non-HDL cholesterol numbers also improved, which matters a lot for long-term heart health.

That said, the drug brought real side effects. Stomach and digestive problems hit hard, especially in the early weeks when doctors slowly raised the dose. More than half of mazdutide users reported vomiting. Close to 47% felt nauseous, and about 39% had diarrhea. Most of these problems were not severe and eased over time, but doctors will need to prepare patients for this adjustment period.

Serious side effects affected 7.2% of people in the mazdutide group, compared to 5.2% in the placebo group. Four people developed gallbladder disease. Doctors found papillary thyroid cancer in two participants, though researchers could not confirm the drug caused it. Nobody developed pancreatitis, and nobody died during the study. Around 3% of people stopped taking mazdutide because of side effects.

The trial also looked at a smaller group of 74 people who had both obesity and type 2 diabetes. The weight loss results for the overall group look encouraging, but this diabetes subgroup was too small to draw strong conclusions about blood sugar outcomes specifically.

A few things limit what we can take from this study. The trial never tested a lower dose, so researchers do not yet know if a smaller amount could still work with fewer side effects. More importantly, every participant was a Chinese adult. People respond differently to drugs depending on their genetics and background, so these results may not apply directly to people in the United States or other parts of the world. Researchers still need to run studies across different populations.

Mazdutide has not gone through FDA review or approval. Reaching that point would take more clinical trials. Still, the GLORY-2 results mark a meaningful step forward for obesity medicine. For doctors following this field, the data suggest that hitting two receptors instead of one could prove smarter, particularly for patients with serious obesity who have not gotten enough help from current treatments.