Free tool
Muscle Loss Risk Calculator
On semaglutide or tirzepatide, a share of every pound lost can come from lean tissue. This tool estimates how exposed you are right now, based on how fast you're losing, how much you're lifting, and how much protein you're getting.
Nothing is stored or sent anywhere. The calculation runs entirely in your browser.
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Please note: These calculators give general estimates from population-level formulas. They are not medical advice. Always consult your prescriber for personalized guidance.
What drives muscle loss on a GLP-1
Studies of semaglutide and tirzepatide consistently find that a meaningful share of total weight lost — often cited between 25% and 40% — comes from lean tissue rather than fat when nothing is done to protect it.
Three things move that number: how fast you're losing, whether you're giving muscle a reason to stay through resistance training, and whether you're eating enough protein to rebuild it. Age and time on medication compound each of those.
How to lower your risk
Aim for a loss rate closer to 1% of bodyweight per week or less. Faster than that and the body starts drawing more heavily on lean tissue for fuel.
Lift something heavy three days a week. Full-body sessions of 20–30 minutes are enough — the signal matters more than the volume.
Get at least 0.7–0.8 g of protein per pound of bodyweight. Appetite suppression makes this the hardest part, so front-load protein early in the day when hunger is highest.