Losing Muscle or Restoring Physiology? Reframing the Incretin Therapy Sarcopenia Concern

The introduction of highly effective incretin-based therapies has transformed obesity management by achieving weight loss previously attainable mainly with bariatric surgery. However, the accompanying reduction in lean body mass has raised concerns regarding treatment-induced sarcopenia, particularly among older adults and other vulnerable populations. In this perspective, we argue that interpreting lean mass loss in isolation may be misleading. Current evidence indicates that approximately one-quarter to one-third of total weight loss consists of lean mass, a proportion comparable to that observed with other effective weight-loss interventions and consistent with physiological body composition remodeling rather than pathological muscle loss. Importantly, incretin therapies preferentially reduce fat mass, improve the lean-to-fat mass ratio, and are associated with improvements in physical function, mobility, and health-related quality of life. These observations challenge the assumption that reductions in lean body mass necessarily translate into clinically meaningful sarcopenia. Nevertheless, skeletal muscle health deserves particular attention in older adults and individuals with pre-existing sarcopenia, frailty, chronic kidney or cardiovascular disease, chronic inflammatory conditions, or poor nutritional status. In these populations, routine assessment of muscle strength and physical performance, together with adequate protein intake and structured resistance exercise, should complement pharmacological obesity treatment. Future research should prioritize muscle quality and function rather than lean mass alone to better define the clinical significance of body composition changes during incretin therapy.