Medications like semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) have become some of the most talked-about weight-loss tools in medicine. They work by mimicking hormones your gut already makes — hormones that help you feel full and regulate your blood sugar. Clinical trials show people losing 15–22% of their body weight on these medications.
But here's something your doctor may not always emphasize: a significant portion of the weight lost on these drugs can come from muscle, not just fat. One major study found that about 39% of the weight lost was lean mass — meaning muscle tissue. Losing muscle is a problem because muscle burns calories, supports your joints, and helps you stay strong as you age.
That's where nutrition comes in. Eating enough protein — found in foods like chicken, fish, eggs, Greek yogurt, lentils, and tofu — helps protect your muscles while you're losing weight on these medications. Research suggests that people on GLP-1 or GIP medications should aim for higher protein than the average person.
Another issue: many people who stop these medications regain most of the weight within a year. The ones who do best long-term are those who used the medications as a window to build better eating habits — not as a replacement for them.
These medications are a powerful tool. Nutrition makes them work better and last longer.