The concern: Studies show 25–40% of weight lost on GLP-1 drugs can be lean mass. The good news: this is largely preventable with the right approach.
How Much Muscle Do You Actually Lose?
In the STEP trials for Wegovy, participants lost an average of 15% body weight — and roughly 25–39% of that loss was lean mass (muscle and bone). This is comparable to other weight loss methods, but still significant.
The concern is that muscle loss can slow metabolism, reduce strength, and make weight regain more likely after stopping the drug.
5 Ways to Preserve Muscle on GLP-1s
Eat enough protein. Aim for at least 1g per pound of target body weight. Protein is the most important muscle-preserving nutrient — most GLP-1 users don't eat enough because appetite suppression reduces overall intake.
Lift weights. Resistance training 2–3x per week is the single best way to signal your body to preserve muscle. Cardio alone won't do it.
Don't cut calories too aggressively. Extreme deficits speed up muscle loss. A moderate deficit of 500–750 cal/day is better than 1,200 cal crash diets.
Consider creatine supplementation. 3–5g/day of creatine monohydrate is well-researched for maintaining strength and lean mass during weight loss.
Track your body composition, not just weight. Scale weight doesn't tell you if you're losing fat vs muscle. A DEXA scan or InBody assessment can show what's actually happening.
Bottom Line
Muscle loss on GLP-1 drugs is real but manageable. The patients who do best combine medication with structured resistance training and adequate protein. Think of the drug as a tool — not a complete solution.