It should come as no surprise that users of weight loss drugs regain weight if they drop out of treatment, according to Sydbank’s senior analyst Søren Løntoft Hansen, after Novo Nordisk competitor Eli Lilly received a harsh reception for its study of the weight loss drug Zepbound.

The US pharmaceutical giant fell 2.3% on the New York Stock Exchange on Monday following the publication of the study.

In Eli Lilly’s Surmount-4 study, Zepbound users who stop taking the drug regain much of the weight they lost after 12 months.

Zepbound is based on the GLP-1 molecule tirzepatide.

Data from the study showed that obese participants lost an average of 20.9% of their body weight after 36 weeks of treatment with 10 or 15 milligrams of tirzepatide. Those who stopped treatment after 36 weeks had only lost 9.9% of their body weight in the following 52 weeks.

The harsh post-study reception for Eli Lilly puzzles Løntoft Hansen.

”I actually think it’s remarkable that the stock is reacting to a study that shows you gain weight again if you drop out of treatment,” he tells Marketwire.

”This is also something that Novo Nordisk has shown in its Step 4 study with Wegovy. It should come as no surprise that if you don’t stay on treatment, you gain weight again,” the senior analyst continues.

The study should contribute to the debate on whether obesity is a chronic disease that requires ongoing treatment, he adds.

On May 13, 2020, Novo Nordisk presented data from phase IIIa of its Step 4 study with Wegovy, which is based on the molecule semaglutide. The study also showed weight loss for users who continued treatment, but also weight gain in those who ceased treatment.

(Translated using DeepL with additional editing by Kristoffer Grønbæk)