Testosterone supplementation and body composition: results from a meta-analysis of observational studies.

PURPOSE The concept of testosterone (T) supplementation (TS) as a new anti-obesity medication in men with testosterone deficiency syndrome (TDS) is emerging. Data from placebo-controlled trials are more conflicting. The aim of this study is to systematically review and meta-analyze available observational and register studies reporting data on body composition in studies on TS in TDS. METHODS An extensive MEDLINE, Embase, and Cochrane search was performed including the following words: "testosterone" and "body composition." All observational studies comparing the effect of TS on body weight and other body composition and metabolic endpoints were considered. RESULTS Out of 824 retrieved articles, 32 were included in the study enrolling 4513 patients (mean age 51.7 ± 6.1 years). TS was associated with a time-dependent reduction in body weight and waist circumference (WC). The estimated weight loss and WC reduction at 24 months were -3.50 [-5.21; -1.80] kg and -6.23 [-7.94; -4.76] cm, respectively. TS was also associated with a significant reduction in fat and with an increase in lean mass as well as with a reduction in fasting glycemia and insulin resistance. In addition, an improvement of lipid profile (reduction in total cholesterol as well as of triglyceride levels and an improvement in HDL cholesterol levels) and in both systolic and diastolic blood pressure was observed. CONCLUSIONS Present data support the view of a positive effect of TS on body composition and on glucose and lipid metabolism. In addition, a significant effect on body weight loss was observed, which should be confirmed by a specifically designed RCT.