Body composition following gender affirming hormone therapy in transgender individuals

Background & objectivesGender-affirming hormone therapy may alter body composition and muscle strength, which may impact participation in sports and other activities. These changes are important to decide whether transgender should have separate categories of competition. MethodsWe conducted this prospective study, to assess the body composition using bioelectrical impedance analysis muscle strength and serum irisin levels at baseline and at 12 months following gender affirming hormone therapy in transgender individuals. The comparisons were done in both cis mode and trans mode. ResultsA total of 32 transfemales and 22 transmales were included in the study. Among transwomen, there was an increase in total subcutaneous fat (9.2%) and visceral fat (11.3 %) (P<0.001 in both cis and trans mode comparison) and a decrease in muscle mass (7.7%) (P=0.033 and P<0.001 in cis and trans mode, respectively) and muscle strength at all sites (P<0.001). Among transmen, there was a decrease in total subcutaneous fat (5.9%) (P<0.001 for both cis and trans mode comparison) and an increase in muscle mass (7.2 %) (P<0.001 for trans mode only) and muscle strength except shoulder abduction on right side (P<0.001). No significant changes were observed in irisin levels following hormonal therapy. Interpretation & conclusionsGender affirming hormonal therapy leads to body fat redistribution after twelve months of hormone therapy with significant alterations in muscle mass and strength among both transmen and transwomen. Irisin, an adipomyokine produced through muscle contraction, did not correlate with muscle mass or fat mass on follow up.