Background: The role of testosterone (T) in regulating body composition is conflicting.
Aim: To meta-analyze the effects of T supplementation (TS) on body composition and metabolic outcomes.
Methods: All randomized controlled trials (RCTs) comparing the effect of TS on different endpoints were considered.
Results: Overall, 59 trials were included in the study enrolling 3029 and 2049 patients in TS and control groups, respectively. TS was associated with any significant modification of body weight, waist circumference and BMI. Conversely, TS was associated with a significant reduction of fat and with an increase of lean mass (standardized means −0.32 (−0.44; −0.19) and 0.51 (0.37; 0.66) for fat and lean mass, respectively; both P<0.0001) as well as with a reduction of fasting glycaemia and insulin resistance (−0.34 (−0.51; −0.17) mM and −0.80 (−1.16; −0.45) for fasting glycemia and HOMA index, respectively; both P<0.0001). The effect on fasting glycaemia was even higher in younger individuals and in those with metabolic diseases. When only RCTs enrolling hypogonadal (total T<12 moles/l) subjects were considered, a reduction of total cholesterol as well as of triglyceride levels were also detected. Conversely, an improvement in HDL cholesterol levels as well as in both systolic and diastolic blood pressure was not observed.
Conclusions: Our data suggest that TS is able to improve body composition and glycometabolic profile particularly in younger subjects and in those with metabolic disturbances. Specifically designed studies are urgently needed to confirm this point.