Eli Lilly & Co.’s experimental weight-loss pill helped patients shed pounds quickly in a mid-stage trial, setting the stage for competition to heat up with rivals such as Novo Nordisk A/S that make obesity drugs.

Lilly’s oral drug, orforglipron, produced an average loss of about 15% of a person’s body weight in 36 weeks when given daily at the highest dose to adults with obesity, according to a mid-stage study published Friday in the New England Journal of Medicine. A pill containing semaglutide, the active ingredient in Novo’s Wegovy shot, produced similar results in a late stage that was almost twice as long.

Lilly and Novo are battling atop a weight-loss market seen growing to as much as $150 billion in sales by 2031, and other companies such as Pfizer Inc. are looking to join in soon. The competition has been sparked by the emergence of drugs called GLP-1s that are mostly available in injectable form, and an effective pill would give Lilly a leg up in the race.

The new medicines, called GLP-1s, were initially developed to treat diabetes, but many people have begun using them as a weight-loss aid because they make people feel full. The field is currently dominated by Novo’s Wegovy and Ozempic, a diabetes injection that many patients use for weight loss. Lilly’s Mounjaro injection is also approved for diabetes, and the company is seeking US market clearance for weight loss, which analysts see bringing billions in sales.

In Lilly’s phase 2 trial, patients who received the experimental pill lost from 9.4% to 14.7% of their body weight, depending on dosing. In an earlier, 68-week trial of oral semaglutide, patients lost 15.1% of their body weight, Novo said in May.

Nausea occurred in 37% to 58% of patients who got Lilly’s pill, depending on the dosing, and vomiting occurred in 14% to 32%, according to the study. Lilly funded the trial that was carried out by researchers in Toronto, Texas, Oklahoma and Indianapolis.