A new study in mice and humans suggests GLP-1 medicines drive weight loss primarily by reducing fat, while preserving muscle function and easing fears about harmful muscle wasting.
Key takeaways
Fat, not skeletal muscle, accounted for most of the weight loss.
According to the study, GLP-1 medicines reduced body fat in obese mice much more than lean body mass, and fat and liver mass fell faster than skeletal muscle.
Muscle function was preserved better than some had feared.
Even though absolute muscle values fell slightly in mice, relative muscle mass and running performance improved. In the 12-week human pilot study, thigh muscle size decreased, but handgrip and knee extension strength did not worsen.
Loss of lean body mass is not the same as loss of skeletal muscle.
The study emphasizes that lean…