In this article, Eli Lilly announced on Wednesday that its obesity drug Zepbound resulted in more weight loss compared to its main competitor, Novo Nordisk’s Wegovy, in the first direct clinical trial involving weekly injections. The results indicate that Zepbound could be a more effective treatment for weight loss, with obese or overweight patients losing an average of 20.2% of their body weight, approximately 50 pounds, after 72 weeks in the phase three trial. In contrast, Wegovy helped individuals lose an average of 13.7% of their weight, around 33 pounds, over the same period.
Eli Lilly reported that Zepbound achieved a 47% higher relative weight reduction than Wegovy in the trial. The company also noted that over 31% of Zepbound users lost at least a quarter of their body weight, while only about 16% of those on Wegovy achieved the same level of weight loss.
Additional studies on the drugs, as well as a recent comparison of health records, have suggested that Zepbound may outperform Wegovy in terms of weight loss. A late-stage study on Zepbound demonstrated an average weight loss of over 22% over 72 weeks, while a separate study on Wegovy showed an average weight loss of 15% over 68 weeks.
The data from Wednesday’s trial represents significant evidence of Zepbound’s superiority, as 751 patients were randomly assigned to receive the maximum dose of either drug. The study focused on patients who were obese or overweight with at least one weight-related medical condition, excluding diabetes.
Dr. Leonard Glass, senior vice president of global medical affairs at Eli Lilly Cardiometabolic Health, stated that the study was conducted to assist healthcare providers and patients in making informed decisions about treatment options. Eli Lilly is currently reviewing the results, intending to publish them in a peer-reviewed journal and present them at a medical conference next year.
The most common side effects of both drugs were gastrointestinal and generally mild to moderate in severity. Eli Lilly’s Zepbound’s superior weight loss is a significant advantage in its competition with Novo Nordisk for a larger share of the growing weight loss drug market, projected to reach $150 billion annually by the early 2030s.
Wegovy entered the market approximately two years before Zepbound, which received approval in the U.S. in late 2023. Despite this, some analysts believe Zepbound has the potential to become the best-selling drug of all time after more years on the market.
GlobalData, a data analytics firm, predicts that Zepbound will generate $27.2 billion in annual sales by 2030, while Wegovy is expected to generate $18.7 billion in annual revenue by the same year, based on data from November.
The demand for Zepbound, Wegovy, and their diabetes counterparts has exceeded supply over the past year, prompting Eli Lilly and Novo Nordisk to invest billions in expanding their manufacturing capacity for the injections. These efforts have been successful, as the Food and Drug Administration now lists all doses of these treatments as “available” on its drug shortage database.
However, some patients face challenges in accessing the drugs due to inconsistent insurance coverage for weight loss treatments in the U.S. Without insurance or other financial assistance, both Zepbound and Wegovy cost around $1,000 per month.
The two treatments operate differently. Zepbound suppresses appetite and regulates blood sugar by activating two gut hormones, GIP and GLP-1. In contrast, Wegovy activates GLP-1 but does not target GIP, which some researchers believe may impact how the body metabolizes sugar and fat.
