Tirzepatide, the active ingredient in Eli Lilly’s Mounjaro and Zepbound , leads to more weight loss than semaglutide, the active ingredient in Novo Nordisk’s Ozempic and Wegovy , new research suggests. The study, published Monday in JAMA Internal Medicine , is thought to be the first head-to-head comparison of the two blockbuster weight loss drugs. Since Zepbound was approved for weight loss in late 2023, it appeared to have an advantage over Wegovy.
Patients taking the highest dose of Zepbound lost around 21% of their body weight over 72 weeks, compared to around 15% for patients on Wegovy after 68 weeks. But it was difficult to make a direct comparison without a study that looked at both drugs, which are part of a new class of medications called GLP-1s. “We’ve tracked GLP-1 use over the last year and we’ve seen really dramatic increases, and yet, there’s not a ton of information available on head to head comparisons,” said lead study author Tricia Rodriguez, a principal applied scientist at Truveta Research, a health care data and analytics company.
In the new study, Rodriguez and colleagues analyzed electronic health records from more than 41,000 adults who were overweight or had obesity and had been prescribed one of the two drugs for the first time. Participants weren't excluded if they had Type 2 diabetes. More than 9,100 were prescribed tirzepatide, and more than 32,000 were prescribed semaglutide.
The researchers looked at how much weight the patients lo.