Patients on Eli Lilly's weight-loss drug substantially regained weight after stopping treatment, according to a study published in journal JAMA on Monday.

The study showed that patients who were obese and without diabetes experienced a 14% weight regain, 52 weeks after switching to placebo from Lilly's tirzepatide.

Lilly's tirzepatide is sold under brand name Zepbound for weight loss and has been available as Mounjaro for type 2 diabetes.

Those who continued the treatment experienced an additional 5.5% weight reduction during the 52-week period, data from the study showed.

Shares of Eli Lilly fell 2% in morning trading.

Data from a Novo Nordisk-funded study in April last year showed that patients regained two-thirds of their lost weight one year after discontinuing the use of the drug.

The new weight-loss drugs belong to a class of treatments known as GLP-1 agonists, which was originally designed to treat type 2 diabetes and have been shown to reduce food cravings and cause the stomach to empty more slowly.