Plasma testosterone and body weight and composition after gonadectomy and testosterone treatment. (A) Plasma testosterone did not differ as a function of sex chromosome complement within sex, but gonadal females had overall 14% higher levels of testosterone (F(1,84) = 4.91, p = 0.029). (B) Gonadal males were about 26% heavier than gonadal females (F(1,84) = 63.13, *p < 0.000001), and XY mice weighed 13% less than XXY irrespective of gonadal sex (F(1,51) = 7.40, *p = 0.009). (C) Gonadal males had 69% more relative fat mass than gonadal females (F(1,84) = 37.75, *p < 0.000001), and there was a significant overall effect of sex chromosome complement (F(3,84) = 4.30, *p = 0.007). XY mice had 43% less relative fat mass than XXY mice (F(1,51) = 13.18, *p < 0.0007), and 21% less than XX mice (F(1,53) = 4.20, *p = 0.045), irrespective of gonadal sex. (D) Relative lean mass was 6% lower in gonadal males than in females (F(1,84) = 29.21, *p = 0.000001, overall ANOVA). In pairwise comparisons, XY had 4% greater relative lean mass than XXY (F(1,51) = 6.63, *p = 0.013). Values are mean ± SEM.