Thirumalai A, et al. - Since serum sex steroid concentrations can alter body composition and glucose homoeostasis in men in a dose-response manner, researchers investigated these end-points in healthy men rendered medically castrated via use of a gonadotrophin-releasing hormone antagonist (acyline) with incremental doses of exogenous testosterone (T) gel. Study participants included healthy men (aged 25–55 years) with normal serum total T concentrations. Investigators randomized participants (6–9 per group) to injections of acyline every 2 weeks plus transdermal T gel (1.25 g, 2.5 g, 5.0 g, 10 g, or 15 g) daily or double placebo (injections and gel) for 12 weeks. They observed that higher serum concentrations of T, dihydrotestosterone, and estradiol were correlated with higher lean mass increases and fat mass decreases in healthy men, but not with changes in serum glucose, insulin or adipokines.