CompanyMade in Detroit | Est. 2026Evidence Library
How much of GLP-1 weight loss is muscle?
Body-composition analyses of GLP-1 trials consistently find that a substantial share of the weight lost is lean mass. The size of the share is the part worth reading carefully.
What was studied
Body-composition substudies and analyses of GLP-1 receptor agonist trials, measuring how total weight loss divides between fat mass and lean mass.
What it showed
A substantial share of the weight lost on GLP-1 medications is lean mass — often a quarter or more, and up to roughly 39 percent in tirzepatide data without preservation protocols. This is why current guidance pairs the medication with high protein intake and resistance training.
What this evidence does not show
The lean-mass share varies by drug, dose, population, and measurement method. These studies describe a risk to manage with protein, training, and medical supervision — they do not show that any supplement prevents the loss.
Sources: Published GLP-1 body-composition analyses and preservation-protocol guidance (protein 1.2-2.2 g/kg/day, resistance training, creatine 3-5 g/day), reviewed October 2026.