Lean Mass Changes With Incretin Therapy Versus Lifestyle Intervention: A Systematic Review and Meta-Analysis of Randomised Controlled Trials.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 41877354 · doi:10.1111/dom.70666
What was done
Authors conducted a systematic review and meta-analysis across PubMed, Embase, Cochrane CENTRAL, and Web of Science through January 2026. They included randomized controlled trials in adults with overweight or obesity evaluating semaglutide, tirzepatide, liraglutide, or lifestyle interventions that assessed body composition by DXA or MRI. The co-primary outcomes were absolute change in lean mass (kg) and the proportion of total weight lost as lean mass, pooled using random-effects models.
What was found
Twenty RCTs including 15,782 participants were analyzed. Lean mass comprised 25% to 39% of total weight lost with incretin agonists: semaglutide 35.2% (95% CI: 31.5–38.9), tirzepatide 25.4% (95% CI: 22.8–28.0), and liraglutide 26.8% (95% CI: 23.1–30.5). Standard lifestyle interventions resulted in a comparable proportion of lean mass loss (26.2% [95% CI: 24.1–28.3]; p = 0.42 vs. incretin therapies). Lifestyle intervention combined with resistance training resulted in the lowest proportion of lean mass loss (17.5% [95% CI: 14.2–20.8]). Heterogeneity was moderate (I² = 68%), and Egger's test showed no evidence of publication bias (p = 0.23).
Why it matters
These findings indicate that the proportional loss of lean mass during incretin-induced weight loss is similar to that seen with conventional lifestyle modification. Incorporating resistance training into weight-loss regimens helps attenuate lean tissue loss.
Limits
Moderate statistical heterogeneity was observed across trials (I² = 68%). The abstract omits numerical values for the co-primary endpoint of absolute lean mass change in kilograms and does not detail intervention durations, specific participant demographics, or method-specific variances between DXA and MRI.
Cited by
- supports GLP-1 medications do not inherently consume or break down muscle and bone tissue directly; any loss of lean mass is due to general weight loss.