Patients taking Novo Nordisk’s (NOVOb.CO), popular Wegovy obesity treatment maintained an average of 10% weight loss after four years on the treatment, the company said on Tuesday.

Novo presented the new long-term data at the European Congress on Obesity in Venice, Italy, gleaned from a large study for which much of the results had been published last year.

“This is the longest study we’ve conducted so far of semaglutide for weight loss,” Martin Holst Lange, Novo’s head of development, said in an interview, referring to the active ingredient in Wegovy and the company’s diabetes drug Ozempic.

“We see that once the majority of the weight loss is accrued, you don’t go back and start to increase in weight if you stay on the drug,” he added.

The data could bolster the company’s case as it tries to convince insurers and governments to reimburse Wegovy and deflect notions that it is a lifestyle drug.

Wegovy was the first to market from a newer generation of medicines known as GLP-1 agonists, originally developed for diabetes, that provide a new way to address record obesity rates. Eli Lilly (LLY.N), launched its rival drug Zepbound in the United States in December. Neither company has been able to produce enough to meet unprecedented demand.

Dr. Simon Cork, Senior Lecturer in Physiology from Anglia Ruskin University, said Britain’s public health service’s decision to limit coverage of the medicine to two years was "because of questionable long-term effectiveness”.

The new data showing benefits continuing to four years may go some way to negating that argument, he said.

The 17,604-patient trial tested Wegovy not for weight loss but for its heart protective benefits for overweight and obese patients who had preexisting heart disease but not diabetes. Participants were not required to track diet and exercise because it was not an obesity study.

Patients in the trial called Select lost an average of nearly 10% of their total body weight after 65 weeks on Wegovy. That percentage weight-loss was roughly sustained year-on-year until the end of about four years, where weight loss stood at 10.2%, the company said.

Wegovy and Zepbound are being tested to assess their benefits in a variety of other medical uses such as lowering heart attack risk and for sleep apnea and kidney disease.

The weight loss in the heart trial was less than the average of 15% weight loss in earlier Wegovy obesity studies before the drug was launched in the United States in June 2021.