Beyond weight loss: a narrative review of tirzepatide’s impact on muscle and lean mass in people with overweight and obesity

The proportion of total weight loss attributable to lean mass generally ranged from 10% to 30%, broadly aligning with expected physiological responses to weight loss. However, substantial heterogeneity in study design, population characteristics, and body composition assessment methods limits the ability to draw definitive conclusions. Most studies relied on indirect measures such as bioelectrical impedance analysis, with limited use of dual-energy X-ray absorptiometry.

Importantly, functional outcomes were not assessed, and the clinical significance of observed lean mass reductions remains uncertain. Overall, tirzepatide appears to promote preferential fat loss, though some loss of lean mass occurs. Strategies such as resistance training and adequate protein intake may help mitigate potential adverse effects on muscle mass during treatment.</p>