Shares of Allurion Technologies climbed after patients treated with its weight-loss program in a clinical study maintained higher muscle mass and had a bigger decrease in fat percentage.

The stock jumped 20% to $3.36 in aftermarket trading. Shares were changing hands at $40.75 this time a year earlier and were down 74% year-to-date when the market closed Tuesday.

The developer of obesity treatments said after the closing bell on Tuesday that 1,962 patients treated in France with the Allurion Program, which uses swallowable gastric balloons, showed muscle mass as a percentage of body weight rising on average by 6.6%, while fat mass decreased on average by 11%.

The company also noted that shipments to France have resumed after its products were pulled last year over safety concerns. The company was cleared to start selling the products again earlier this year.