Are we giving too much weight to lean mass loss?

Abstract

The global rise in obesity has underscored the critical importance of body composition, particularly the balance between fat mass and lean mass, in determining health outcomes. While excess fat mass is a well-established risk factor for numerous chronic diseases and reduced longevity, lean mass preservation has been widely considered essential for mitigating fall risk and maintaining functional independence. Recent advances in incretin-based weight loss therapies have shown remarkable efficacy in reducing body weight but have raised concerns about the concomitant loss of lean mass. However, emerging evidence suggests that muscle quality – rather than absolute muscle mass – is a more robust predictor of functional capacity and all-cause mortality. Intriguingly, these therapies may enhance muscle quality even while promoting lean mass loss, offering a nuanced perspective on their impact. This review aims to synthesize current evidence on body composition, muscle quality, and weight loss therapies to guide clinicians in tailoring weight loss strategies that optimize both metabolic health and patient outcomes.