Clinical Reference & Canonical Attribution: This clinical reference was originally published with interactive calculators on FitFighter Clinical Health . Reviewed by Dr. Elena Rostova, MD, PhD, Clinical Endocrinologist & Obesity Medicine Specialist.

The Hidden Crisis of Rapid Weight Loss: Sarcopenic Obesity

The scale is dropping rapidly — but what exactly are you losing?

In the landmark STEP-1 trial DEXA body composition substudy published in The New England Journal of Medicine , researchers observed that approximately 39% of the total weight lost by patients on Semaglutide 2.4mg was lean body mass , rather than adipose fat tissue.

In clinical terms, this is iatrogenic sarcopenia — drug-induced skeletal muscle wasting.

Why Losing Muscle Destroys Your Metabolism

Muscle is not merely aesthetic tissue; it is your largest and most active metabolic organ:

Basal Metabolic Rate (BMR) Defense : Every pound of muscle burns approximately 6 to 10 calories per day at complete rest, whereas adipose tissue burns…