Macro partitioning
GLP-1RAs and GIP/GLP-1RAs (liraglutide, semaglutide, tirzepatide) cause significant loss of fat-free (muscle) mass in older adults with sarcopenic obesity, posing a risk that may outweigh benefits if not managed.
If you are an older adult with sarcopenic obesity considering GLP-1 medications, expect to lose some muscle along with fat. To protect your strength, you must combine the medication with regular resistance exercise and eat enough protein (1.0-1.2g per kg of body weight). Work with your doctor to start slowly and monitor your function.
These medications come with the risk of loss of muscle mass and an increased rate of adverse events. ... Trials to test subjective physical function included use of the physical functioning score ... Within a subgroup whose body composition was measured with DXA ... participants taking semaglutide lost 3.6% of their fat-free mass, vs. 0.1% in the placebo group ... participants treated with tirzepatide lost 10.9% of their fat-free mass compared with 2.6% in the placebo group.
Why this rating
Evidence is derived from subgroup analyses of younger populations and secondary analyses; direct RCTs on sarcopenic obesity are lacking.
Source
Treating Sarcopenic Obesity in the Era of Incretin Therapies: Perspectives and Challenges
Alissa S. Chen et al. · Diabetes · 2025
DOI 10.2337/dbi25-0004
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