If you're losing weight with retatrutide but not eating enough protein or doing strength training, you might lose a lot of muscle because your body starts breaking it down.

People with obesity who took a shot called retatrutide once a week for a year lost nearly a quarter of their body weight—way more than those who got a dummy shot. This makes it one of the strongest weight-loss medicines we’ve seen so far.

Retatrutide keeps helping people lose weight steadily for a whole year without slowing down, while other weight-loss drugs like GLP-1s tend to stop working as well after a few months.