#Lean-Mass

2 stories

Research October 22, 2026 · View digest

Meta-Analysis of Five Phase 3 Trials Finds Lean Mass About 3.4 to 4.4 kg Lower on Semaglutide 2.4 mg and Tirzepatide Than Placebo, With Wide Uncertainty

A meta-analysis published October 21, 2026 in BMC Endocrine Disorders pooled DXA body-composition data from five Phase 3 trials with 569 adults. In the two placebo-controlled obesity trials (semaglutide 2.4 mg and tirzepatide, 68 to 72 weeks), lean body mass was 3.43 and 4.40 kg lower and fat mass 6.99 and 12.30 kg lower than with placebo, but the pooled lean-mass estimate (-3.95 kg) had a 95% confidence interval crossing zero. Across all five trials, lean mass was 2.49 kg lower, a result that lost statistical significance when any one of three trials was dropped; DXA lean mass also includes water and organ tissue, not just muscle.

Research June 14, 2026 · View digest

ENDO 2026 Study: GLP-1 Users Walk 560 Fewer Steps Per Day, Lose 5.7 Minutes of Moderate-to-Vigorous Activity

A Stanford-led retrospective pre-post cohort study presented June 13 at ENDO 2026 in Chicago used NIH All of Us Research Program data linking electronic health records with Fitbit activity in 1,950 adults with obesity who started GLP-1 medications. Among the 753 with sufficient wearable data, mean daily steps dropped from 5,047 before GLP-1 initiation to 4,487 after (-560 steps, p<0.001); moderate-to-vigorous activity fell from 27.9 to 22.2 minutes per day (-5.7 minutes, p<0.001). The largest declines occurred in men and in people with pre-existing joint or muscle pain; age, heart failure, and stroke history did not change the pattern. Lead author Surya Maharjan flagged the activity drop as a concern given GLP-1-associated lean-mass loss.