Does semaglutide cause muscle loss?

Any rapid weight loss — including on semaglutide or tirzepatide — can include some loss of lean muscle along with fat, especially if protein intake is low and you are inactive. It is not caused by the drug directly, and it is largely preventable with adequate protein, resistance training, and physician-guided dosing.

Why it happens

When you eat in a calorie deficit, your body can break down muscle for energy if it isn't getting enough protein and a stimulus to keep muscle. Because GLP-1s sharply reduce appetite, some people unintentionally eat too little protein.

How to protect muscle

Eat protein first at each meal and aim for a consistent daily target. Include resistance activity 2–3 times per week. Lose weight at a steady, physician-recommended pace rather than as fast as possible. Preserving muscle also protects your resting metabolism, which helps prevent plateaus.

Medically reviewed by Dr. Michael Mimlitz, MD (NPI 1508891870), Chief Physician of GOAL.MD. Physician-supervised telehealth. More at goal.md/answers.