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

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.

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.

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.

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.