Variable Effects of Glucagon Like Peptide-1 Receptor Agonists on Body Composition in Older Women.

BACKGROUND/OBJECTIVE: Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) improve glycemic control, promote weight loss, and enhance cardiovascular outcomes. However, their effects on lean mass in older adults are unclear. This case report describes how GLP-1 RAs influenced body composition in 2 older women. CASE REPORT: We measured the body compositions of 2 older women with obesity, who were unable to lose weight through lifestyle changes alone, before and after taking GLP-1 RAs. The first patient (65 years old) received weekly subcutaneous injections of tirzepatide. She had a moderate reduction in body mass index over 4 months, with a modest reduction in fat mass and a substantial reduction in lean mass. The second patient (79 years old) received weekly subcutaneous injections of semaglutide and had a moderate reduction in body mass index over 6 months, with a substantial reduction in fat mass and a modest gain in lean mass. The patient with greater muscle loss was less physically active and tracked food intake less precisely than the patient with less muscle loss. DISCUSSION: Differences in lean mass loss between patients may be influenced by exercise and calorie counting. These findings highlight the importance of lifestyle modifications for preserving lean mass. However, because only 2 patients were studied, the results are entirely anecdotal and therefore cannot be generalized to larger populations. CONCLUSION: Clinicians should consider recommending individualized exercise programs and dietary strategies for older patients taking GLP-1 RAs. Routine assessment of body composition may help guide interventions and optimize clinical outcomes.