Effects of weight loss on testosterone, sex hormone-binding globulin, adiposity, and insulin sensitivity in women and men.

Abstract

Testosterone and glucose disposal (Rd) are positively associated in adult men, whereas the opposite is reported in women. Sex-specific relationships between testosterone or sex hormone-binding globulin (SHBG) and Rd in men and women with and without obesity and following weight loss were examined. Adult men and women (n = 27/28; BMI = 20-41 kg/m²) underwent measurements of body composition, Rd, SHBG, and bioavailable (BioA) and total testosterone. Men and women (n = 17/15) with obesity completed a 16-week dietary weight-loss program with repeat testing. BioA testosterone was lower in men with obesity and was related to Rd positively in men and negatively in women (p < 0.05). Across participants, weight loss increased Rd and SHBG (p < 0.01). BioA testosterone was unchanged in men; however, individual changes were independently related to Rd (p = 0.031). In women, BioA testosterone declined (p < 0.009) but was not related to Rd. BioA testosterone was associated with Rd, positively in men and negatively in women. Weight loss reduced BioA testosterone in women; however, individual changes were associated with improved Rd in men. SHBG was a better correlate of improved Rd in women. Additional studies should identify mechanisms that drive sex differences and interventions that modify testosterone, reduce adiposity, and improve Rd across both sexes.