SUN-666 Sex-based Differences In Body Composition Changes Among Adolescents With Obesity Under Glp-1 Analogue Therapy

Abstract Disclosure: A. Lopez: None. O. Borger: None. Y. Issan: None. H. Interator: None. M. Yackobovitch-Gavan: None. E. Cohen-Sela: None. E. Azoulay: None. L. Perl: None. H. Moran-Lev: None. R. Lubetzky: None. Y. Lebenthal: None. A. Brener: None. Introduction: Glucagon-like peptide-1 analogues (GLP-1a) have been approved for the treatment of obesity in individuals aged 12 years and older, representing an important advancement in pediatric obesity management. While studies have demonstrated an improvement in body mass index (BMI), the effects of GLP-1a on body composition remain unclear. In this study, we evaluated changes in body composition components during weight reduction processes in adolescents with obesity, treated and non-treated with GLP-1a. Methods: This real-world study involved patients aged 12 years and older with obesity who were treated and monitored at the Institute of Pediatric Endocrinology between 1/2020 and 3/2025. Routine medical care was delivered by a multidisciplinary obesity team, providing guidance in personalized nutritional and physical activity. GLP-1a therapy (liraglutide or semaglutide) was prescribed, with consent, as an adjunct to a healthy lifestyle when medically indicated, with individualized dosing and management. Z-scores for anthropometric measures (BMI) and body composition parameters assessed via bioimpedance analysis [appendicular skeletal muscle mass (ASMM) and muscle-to-fat ratio (MFR)] were collected at 3 time points: 6 months prior to GLP-1a initiation, at initiation, and during treatment. The same time points were used for comparison with individuals not receiving GLP-1a treatment. Linear repeated measures mixed models were used to analyze the effects of GLP-1a therapy on changes in BMI and body composition parameters. All models were adjusted to sex, age and socioeconomic position. The models were stratified according to sex when sex was found to be significant in the model. Results: Forty-one (61.2%) of the 67 adolescents (39 girls, 58%) included in this study received GLP-1a treatment. The baseline mean BMI z-score was 2.46 ± 0.82. There was a significant reduction in the BMI z-score only in the GLP-1a-treated group after treatment initiation (p = 0.032 vs p=0.998 in the untreated group), with no differences between sexes. The baseline mean ASMM z-score of the entire cohort was −1.12 ± 0.89, with a significant improvement observed only in GLP-1a-treated boys after treatment initiation (p=0.004). The baseline mean MFR z-score was −1.85 ± 0.48, with improvement following GLP-1a initiation only in boys (p=0.019). Conclusion: GLP-1a treatment resulted in significant weight loss in adolescents with obesity seeking medical care. Although both sexes showed comparable reductions in BMI z-scores under therapy, body composition changes differed, with boys experiencing greater gains in muscle mass and muscle-to-fat ratio. These findings suggest potential sex-specific metabolic benefits of GLP-1a therapy. Presentation: Sunday, July 13, 2025