People taking Eli Lilly’s weight-loss drug Zepbound lost more pounds than those taking Wegovy, made by Novo Nordisk, in a head-to-head clinical trial, Lilly reported Wednesday in a news release.
The study, funded by pharmaceutical company Lilly, is the first randomized, controlled clinical trial comparing the two rival weight loss drugs. Previous studies have shown that Zepbound outperforms Wegovy for weight loss; however, they were not considered true comparisons as they were based on existing data.
According to the results of the Lilly trial, patients who received weekly injections of Zepbound lost an average of 20.2% of their body weight, or 50.3 pounds, after 72 weeks, compared to an average of 13.7% of their body weight, or 33.1 pounds of those received by Wegovy.
This means, according to Lilly, that Zepbound provides 47% more weight loss than Wegovy.
Dr. Susan Spratt, an endocrinologist and medical director of the Office of Population Health Management at Duke Health in North Carolina, said that although Zepbound provides more weight loss than Wegovy, both drugs are very effective.
“The weight loss with both is amazing,” Spratt said.
Wednesday’s results were announced in a news release and have not yet been subject to expert review. Lilly said it plans to present the results at a medical meeting next year.
In a statement, a Novo Nordisk spokesperson noted the heart benefits of Wegovy, stating that “in combination with diet and exercise, Wegovy is the only anti-obesity medication shown to reduce the risk of major cardiovascular events, including death, myocardial infarction or stroke.”
The results were based on 751 adults from across the United States, including Puerto Rico, who were randomly assigned to receive one of the two highest doses of Zepbound or Wegovy. People were overweight or obese.
Eli Lilly said the most commonly reported side effects for both Zepound and Wegovy were gastrointestinal related and “generally mild to moderate in severity.”
Dr. Christopher McGowan, a gastroenterologist who runs a weight loss clinic in North Carolina, said the side effects for both Zepbound and Wegovy are generally comparable, although his patients tend to say they do better on Zepbound.
Side effects of the drugs can include gastrointestinal problems, such as abdominal pain, nausea, and vomiting.
Zepbound contains the active ingredient tirzepatide, the same substance used in Mounjaro, Lilly’s diabetes medicine. Wegovy contains semaglutide, the same drug as Novo Nordisk’s Ozempic.
Both act in a similar way: GLP-1 drugs mimic a hormone that helps reduce food intake and appetite.
However, tirzepatide also mimics a second hormone, GIP, which, in addition to reducing appetite, is thought to improve the way the body breaks down sugar and fat.
Spratt added that he would like to see more data comparing the drugs with health outcomes beyond weight loss.
Wegovy, for example, has been shown to reduce the risk of heart disease in people who are overweight or obese. Zepbound has been shown to be a possible treatment for obstructive sleep apnea.
“I don’t think that was the goal of this trial, but it will be important in deciding which drug to recommend,” Spratt said.
McGowan said weight loss isn’t the only factor patients consider.
“Most patients seeking GLP-1 treatment choose what they can get based on cost, availability and insurance coverage,” he said. “Very few patients can be picky right now.”
