Eli Lilly and rival Novo Nordisk are racing to expand their weight loss drug uses and approval in the US, one of their largest markets|Eli Lilly and Company|Facebook

For the first time, researchers compared Eli Lilly’s obesity drug Zepbound and Novo Nordisk’s Wegovy in a head-to-head 751-person trial. The study found that patients taking Zepbound lost 47% more weight than those given Wegovy.

The trial, sponsored by Eli Lilly, involved obese or overweight people, and those administered Zepbound lost an average of 20% of their weight over 72 weeks, compared to ~14% for the test group treated with Wegovy. The subjects also had illnesses like heart disease or sleep apnea but not diabetes.

Side effects for both drugs were mild-to-moderate gastrointestinal issues.

The findings haven’t been peer-reviewed yet or published; complete results of the trial are expected to come out next year.

The Biden administration plans to add Medicare and Medicaid coverage for weight-loss treatments in 2026, but Zepbound’s edge may give it preferential status.

Lilly and rival Novo are racing to expand their weight loss drug uses and approval in the US, one of their largest markets. The companies currently sell these medications under different brand names—Novo’s Ozempic and Lilly’s Mounjaro—to treat type 2 diabetes.