03/09/2026
You’ve probably heard people say GLP-1 medications cause muscle loss. That is just not true.
These headlines claim that 40% of lean body mass is lost during weight loss with GLP-1s, but these results come from studies using inappropriate methods, using body composition tools like:
DEXA scans
Bioelectrical Impedance measures
and MRI
Here’s the problem:
These tools measure lean mass, not muscle cells.
Lean mass is
Muscle
Water
connective tissue
Glycogen
And fat stored inside muscle tissue
When you lose weight, several things change:
The fat inside the cell shrinks by about 30%
Muscle water content decreases because of a decrease in glycogen levels
And inflammation goes down
That’s not muscle loss. That’s muscle getting leaner and more efficient.
One study shows that muscle strength is preserved during medically assisted weight loss.
So the big limitation of these studies is that they didn’t directly measure the following:
muscle fiber cross-section
Muscle cell number
contractile protein content, proteins that generate force and movement in cells
or strength relative to body weight
Until we have proof, saying “GLP-1s cause muscle loss” is an oversimplification.
So here is my message. GLP-1 medications are life-saving and help people lose weight, reverse disease, and achieve metabolic numbers on their labs that would otherwise be impossible with diet and exercise alone.
References
Bianchi, V. E. Weight loss is a critical factor to reduce inflammation. Clinical Nutrition ESPEN.
Gray, R. E., et al. Effect of weight loss on muscle lipid content in morbidly obese subjects. American Journal of Physiology-Endocrinology and Metabolism.
Hackney, K. J., et al. Skeletal muscle volume following dehydration induced by exercise in heat. Extreme Physiology & Medicine.
Han Na Jung, Kim, et al. Preserved Muscle Strength Despite Muscle Mass Loss After Bariatric Metabolic Surgery: a Systematic Review and Meta-analysis. Obesity Surgery.
