If older people lose a lot of muscle while taking weight-loss drugs like semaglutide or tirzepatide, it might raise their risk of weakness, falls, and even earlier death because muscle helps keep the body strong and burning calories.

Medicines like semaglutide and tirzepatide help people lose a lot of weight—up to a quarter of their body weight—but they also cause some muscle loss, about as much as you’d normally lose in 10 years of aging.

Some newer weight-loss drugs help people lose a lot of weight—up to a quarter of their body weight—but they might also cause a big drop in muscle, about as much as people usually lose in 10 years of aging, which could make them weaker over time.

If you keep your muscle while losing weight with certain diabetes or weight-loss drugs, you might be less likely to gain the weight back after stopping the drug — because more muscle helps you burn more calories even when resting.