How much lean mass do people typically lose on GLP-1?

In published trials of semaglutide and tirzepatide, lean mass commonly accounts for a meaningful share of total weight lost, in some analyses up to roughly 40 percent without any intervention. The number varies by age, sex, training history, and protein intake. Older adults and sedentary people tend to lose a larger share as lean mass; younger adults who train and eat enough protein hold on to most of theirs. The trial averages do not have to be your story. Hitting 1.2 to 1.6 grams of protein per kilogram per day, paired with two to four resistance sessions a week, drops the lean-mass share substantially. A DEXA scan every 3 to 6 months is the only way to know which side of the average you are on.