Four in ten lost a fifth of their body weight entirely.
In a country where obesity rates have quadrupled over three decades, a two-year phase 3 trial across 27 Chinese hospitals has offered a meaningful new answer to an urgent question. Mazdutide, a synthetic compound that simultaneously activates two metabolic pathways, helped Chinese adults with obesity lose an average of 16.65% of their body weight — a result that dwarfs the 1.50% seen with placebo. The findings, published in JAMA, suggest that pulling two biological levers at once may reshape not just the number on a scale, but the deeper metabolic landscape beneath it — though the cost of that reshaping, for many, includes significant gastrointestinal discomfort.
- China's obesity epidemic has quadrupled in 30 years, creating pressure to find treatments that work specifically in Chinese adults with moderate-to-severe obesity — a gap this trial was designed to fill.
- Mazdutide's results are striking: 84.3% of participants lost at least 5% of their body weight, and 42.4% lost a fifth of their body weight entirely, while placebo recipients barely moved the needle.
- Beyond weight, the drug reshaped cardiometabolic risk — waist circumference shrank by nearly 13 centimeters, systolic blood pressure fell by 10 points, and triglycerides dropped by 20%.
- The side effect burden is real and common: more than half of participants experienced vomiting, nearly half reported nausea, and four in ten had diarrhea — though most cases were mild and clustered in early dose-escalation weeks.
- Rare but serious signals — four cases of acute gallbladder disease and two cases of papillary thyroid cancer — require careful watching as the drug moves toward broader use.
- The trial's results are currently limited to Chinese adults at a single dose level, leaving open questions about other populations, lower doses, and long-term safety that future research must answer.
A new obesity drug has cleared a major hurdle in China. Over 60 weeks, researchers tested mazdutide — a once-weekly injection that activates two separate metabolic receptors simultaneously — in 461 Chinese adults with significant excess weight across 27 hospitals. The results, published in JAMA, are difficult to dismiss: participants lost an average of 16.65% of their body weight, compared to 1.50% in the placebo group.
The numbers behind that headline are equally striking. More than four in five people taking mazdutide lost at least 5% of their body weight — a threshold clinicians consider genuinely meaningful for health outcomes. Nearly three-quarters lost 10% or more. Four in ten lost a full fifth of their body weight. The drug also reshaped the metabolic terrain underneath: waist circumference shrank by nearly 13 centimeters, systolic blood pressure fell by close to 10 points, triglycerides dropped by 20%, and LDL cholesterol declined by nearly 7%.
What sets mazdutide apart mechanically is its dual action. It activates both the GLP-1 receptor — the same pathway targeted by now-famous weight-loss drugs — and the glucagon receptor, effectively pulling two levers at once. The compound is a synthetic version of oxyntomodulin, a natural hormone involved in appetite and energy regulation. The theory is that combining both pathways produces effects neither could achieve alone.
The urgency behind this research is real. China's obesity rates have quadrupled over 30 years, and most weight-loss drugs have been studied in broader global populations rather than specifically in Chinese adults with moderate-to-severe obesity. This trial was designed to fill that gap.
But the drug carries a significant side effect burden. More than half of participants reported vomiting, nearly half experienced nausea, and four in ten had diarrhea. Most cases were mild to moderate and concentrated in the early weeks of dose escalation, and only 2.9% of participants stopped treatment because of side effects. Still, four cases of acute gallbladder disease and two cases of papillary thyroid cancer emerged — findings that warrant careful monitoring as the drug moves forward.
The trial's limitations are worth noting: results apply only to Chinese adults, the diabetic subgroup was too small to draw firm conclusions, and only the 9-milligram dose was tested. Whether lower doses might achieve similar weight loss with fewer gastrointestinal effects remains an open question. For now, the data suggest mazdutide has earned a place in the obesity treatment conversation — at least for the population in which it was studied.
A new obesity drug has cleared a major hurdle in China. In a phase 3 trial spanning two years across 27 hospitals, researchers tested mazdutide—a synthetic compound that works on two separate biological pathways at once—in 461 Chinese adults carrying significant excess weight. The results, published in JAMA, show the drug produced weight loss that is both substantial and consistent across a broad population.
Participants who received a once-weekly 9-milligram injection lost an average of 16.65% of their body weight over 60 weeks. Those on placebo lost 1.50%. The gap is not marginal. More than four in five people taking mazdutide shed at least 5% of their body weight—a threshold clinicians consider meaningful for health. Nearly three-quarters lost 10% or more. Four in ten lost a fifth of their body weight entirely. By comparison, one in three placebo recipients hit the 5% mark.
The drug's reach extends beyond the scale. Waist circumference—a marker of dangerous belly fat—shrank by nearly 13 centimeters in the mazdutide group versus 2 centimeters in placebo. Systolic blood pressure fell by nearly 10 points. Triglycerides dropped by a fifth. LDL cholesterol, the kind that hardens arteries, declined by nearly 7%. These are the numbers that matter to cardiologists: the drug appears to be reshaping not just weight but the metabolic terrain underneath it.
The mechanism behind mazdutide is what sets it apart from existing obesity treatments. It is a dual agonist, meaning it activates two different receptors in the body simultaneously—the GLP-1 receptor and the glucagon receptor. GLP-1 drugs have become household names in recent years, but mazdutide adds a second lever. The compound is a synthetic version of oxyntomodulin, a natural hormone that regulates appetite and energy use. The theory is that pulling two levers at once produces effects neither alone could achieve.
China faces a particular urgency around this question. Over the past 30 years, obesity rates in the country have quadrupled. Adults with a BMI of 30 or higher—the threshold used in this trial—carry elevated risk of heart disease, stroke, and early death. Yet most weight-loss drugs tested in China have been studied in broader populations, not specifically in people with moderate-to-severe obesity. This trial filled that gap, enrolling only those with a BMI of 30 or above, with a small subset also carrying type 2 diabetes.
But the drug comes with a cost. More than half of those taking mazdutide reported vomiting. Nearly half reported nausea. Four in ten experienced diarrhea. These are not rare side effects tucked into fine print—they are common. The good news is that most were mild to moderate and clustered in the early weeks when doses were being increased. Only 2.9% of participants stopped taking the drug because of side effects. No deaths occurred. Serious adverse events were slightly more common in the mazdutide group (7.2% versus 5.2%), though the trial was not powered to determine whether this difference is real or chance. Four cases of acute gallbladder disease emerged, and two participants developed papillary thyroid cancer, though the latter finding requires careful interpretation in a trial of this size.
The researchers acknowledge important limitations. The trial included only Chinese adults, so it remains unclear whether these results would hold in other populations. The small number of participants with diabetes—74 out of 461—means conclusions about the drug's effect on blood sugar control are tentative. And the trial tested only the 9-milligram dose, leaving open questions about whether lower doses might produce similar weight loss with fewer gastrointestinal effects.
Still, the data suggest mazdutide has a place in the obesity treatment arsenal, at least for Chinese adults with significant weight to lose. The next step will be managing the side effects in practice—perhaps through slower dose escalation or other strategies—and testing whether the drug works as well in other populations facing the same epidemic.
Notable Quotes
Most gastrointestinal adverse events were mild to moderate in severity and occurred primarily during the initial dose-escalation period.— GLORY-2 trial findings
The Hearth Conversation Another angle on the story
Why does a drug that makes half its users vomit count as a success?
Because the vomiting happens early and then mostly stops, and because the alternative—for people with severe obesity—is often nothing that works at all. The weight loss is real and sustained. For many people, that trade is worth making.
But why test it only in China? Doesn't that limit what we actually know?
It does. China has a specific obesity crisis and specific healthcare infrastructure. Testing there first makes sense. But you're right that we won't know if a Chinese body responds the same way as a European or African body until someone runs those trials.
The drug works on two pathways instead of one. Is that why it's better than existing drugs?
Possibly. The theory is elegant—activate appetite suppression and energy expenditure simultaneously. But we don't have a head-to-head comparison yet. We only know it works better than doing nothing.
What worries you most about these results?
The gallbladder disease cases and the two thyroid cancers. In a trial of 307 people, two cancers is a small number, but it's not zero. We need to watch whether that signal holds up in larger populations.
Who needs this drug most?
Someone with a BMI over 30 who has tried diet and exercise and still carries dangerous weight. Someone whose blood pressure and cholesterol are climbing. Someone for whom the gastrointestinal side effects are a price they're willing to pay for the chance at real change.