By Naomi Kresge | Bloomberg
Eli Lilly & Co.’s obesity drug Zepbound helped people trim about two inches more off their waists than Novo Nordisk A/S’s Wegovy in the first head-to-head study of the rival medicines.
Zepbound won on all measures of effectiveness in a trial presented Monday at an obesity conference, spurring an average of 47% more weight loss over 72 weeks.
Lilly, which funded the research, is leapfrogging Novo in the booming market for powerful new obesity medicines. The impact on waistlines is crucial because they are a surrogate measure for the dangerous fat that gets stored around organs in the abdomen.
Novo shares fell as much as 8.6% in Copenhagen trading, more than other drugmakers after US President Donald Trump said he plans to order a cut in US prescription drug costs. The stock has struggled this year, losing about a third of its value.
The study findings could influence prescribing decisions, said Louis Aronne, the NewYork-Presbyterian Hospital physician and Cornell University professor who led the study.
“It’s been shown that a five-centimeter (2-inch) difference could reduce blood pressure and other metabolic parameters,” Aronne said. Patients lost an average of 18.4 centimeters around their waists on Zepbound and 13 centimeters on Wegovy.
Belly fat is linked to a higher risk of diseases such as heart attacks, strokes and diabetes, so doctors recommend that a person’s waistline be no more than half their height.
“If you have more abdominal fat, you are much more likely to also have more fat in your liver, in your muscle and in your heart,” said Gijs Goossens, professor of the cardiometabolic physiology of obesity at Maastricht University. He wasn’t involved in the study.
More women
The research is being presented at the European Congress on Obesity in Malaga, Spain. Lilly disclosed the initial weight loss results last December.
Novo noted that Wegovy is approved to help prevent strokes and heart attacks, saying in a statement that “obesity is about more than just a number on a scale.” The Danish company said it will seek approval in Europe later this year for a higher-dose version of Wegovy that showed 20.7% weight loss in a study.
Although Novo was first to market with Wegovy and its sister drug Ozempic for diabetes, Lilly has gained the lead in obesity prescriptions with Zepbound. The US company’s diabetes version of the drug, Mounjaro, is on track to catch up with Ozempic as well by next August, according to Evan Seigerman, a BMO Capital Markets analyst.
Patients in the study who took Zepbound were twice as likely as the Wegovy group to lose at least 25% of their body weight. About four-fifths of Zepbound patients lost at least 10%, compared to about three-fifths of Wegovy patients. Side effects were similar, though far more Zepbound patients reported pain or swelling at the site of the shot and slightly more Wegovy patients stopped treatment because of side effects such as nausea and vomiting.
Patients in the study weighed an average of 113 kilograms (249 pounds). Almost two-thirds of them were female — a smaller proportion of women than in some studies of obesity medicines. Women typically lose more weight on Zepbound and Wegovy than men do.
Doctors will probably want to consider detailed results on how the two medicines compare across different types of patients before making decisions about what to prescribe, according to Goossens. What weight-loss drug people get may wind up being a case-by-case decision, he said.
Lilly plans to share more breakdowns on specific patient populations next month at the American Diabetes Association meeting in Chicago, said Leonard Glass, who heads the drugmaker’s cardiometabolic health global medical affairs. The company is also studying Zepbound’s impact on illness and death in a trial that’s due to deliver results in 2027.
Patients who are more obese may ultimately do better with Zepbound, said Aronne, who has also advised Novo Nordisk. However, the head-to-head results still leave plenty of room for doctors to use Novo’s drug, he said.
“I’m not trying to minimize the effect of semaglutide,” Aronne said, using Wegovy’s generic name. “The majority of people with obesity will do just fine.”
–With assistance from Madison Muller at Bloomberg.
