Eli Lilly and Co (NYSE:LLY)’s weight loss drug Zepbound (tirzepatide) has shown superior results compared to Novo Nordisk (NYSE:NVO)’s Wegovy (semaglutide) in a direct clinical trial, marking the first head-to-head comparison between the two leading obesity treatments.
In the 72-week trial, participants on Zepbound lost an average of about 50 pounds (22.8 kg), equating to approximately 20.2% of their body weight.
In comparison, those taking Wegovy lost an average of 33 pounds (15 kg), or about 13.7% of their body weight. This represents a 47% greater relative weight loss for Zepbound over Wegovy.
Zepbound also led to a higher proportion of participants achieving significant weight loss. About 64.6% of users lost at least 15% of their body weight, compared to 40.1% for Wegovy.
In terms of waist circumference, Zepbound reduced measurements by an average of 18.4 cm, versus 13 cm for Wegovy.
Both medications reported similar safety profiles, with mild to moderate gastrointestinal side effects being the most common.
"These data confirm Zepbound as a leading treatment option for people living with obesity and equip healthcare providers with critical insights to make well-informed treatment decisions as part of a comprehensive obesity care plan," Eli Lilly senior vice president of global medical affairs Dr Leonard Glass said in a statement.
Novo Nordisk responded to the trial results by noting that the weight loss observed with Wegovy in this recent comparison was less than what had been recorded in a similar 2021 study using the same dosage.
The company said that "obesity is more than a number on a scale," highlighting that Wegovy remains the only GLP-1 agonist approved to reduce major cardiovascular events such as heart attacks.
Novo Nordisk also pointed out that a recent trial with a higher dose of semaglutide showed more significant weight loss results, suggesting that higher doses could improve outcomes further.
Shares of Eli Lilly traded modestly lower, down 0.2% at $732, in early trade on Monday, while Novo Nordisk was down 0.5% at $65.