Body composition, metabolic syndrome, and lifestyle in treatment-naïve gender-diverse youth in Israel

Background: There is a scarcity of published studies evaluating transgender/gender-diverse youth before initiating gender-affirming hormones. Aim: To study the body composition, metabolic syndrome (MetS) components and lifestyle habits in treatment-naïve transgender youth. Methods: Cross-sectional study evaluating 153 transgender youth [median age 15.7 years, 94 transgender males] who attended The Israeli Children and Adolescents Gender Clinic between 6/2021–12/2022. Clinical, metabolic data and lifestyle habits (diet, physical activity and sleep patterns) were retrieved from the medical files. Body composition was determined by bioelectrical impedance analysis. Body mass index and muscle-to-fat ratio z-scores were calculated by sex designated at birth. Results: Weight categories differed between genders, with a greater proportion of subjects classified as underweight among transgender females, and a greater proportion affected by overweight/obese/severe obese among transgender males (p = 0.035). The odds for MetS components were increased by 2.2 for every 1 standard deviation decrease in the muscle-to-fat ratio z-score (95%CI: 1.45 to 3.26, p < 0.001). About one-third of the cohort did not meet any of the three lifestyle recommendations. Transgender males had increased odds for MetS components by 3.49 (95%CI: 1.63 to 7.44, p = 0.001). Conclusions: Treatment-naïve transgender-male adolescents have an imbalance between muscle and adipose tissue, which places them at increased susceptibility for MetS components even prior to hormonal treatment.