Important lessons about testosterone therapy- weight loss vs. testosterone therapy for symptom resolution, classical vs. functional hypogonadism, and shortterm vs. lifelong testosterone therapy.

In this commentary, we highlight important findings from a notable RCT by Ng Tang Fui et al. 2016 which investigated the effects of testosterone treatment in dieting obese men. First, a myopic focus on weight loss can detract from important improvements in body composition. Second, while weight loss in obese men may increase testosterone levels, this increase is commonly not enough to result in an improvement in symptoms associated with testosterone deficiency. Third, the RCT by Ng Tang Fui et al. adds evidence to the growing number of clinical trials showing that testosterone therapy should not be restricted to men with classical hypogonadism. Finally, the beneficial effects of testosterone therapy are not maintained after cessation of treatment. Currently, the British Society for Sexual Medicine guidelines are the only clinical guidelines which acknowledge that weight loss per se does not automatically translate to resolution of hypogonadal symptoms, that testosterone therapy can greatly benefit men with testosterone deficiency who do not have classical hypogonadism, and that cessation of testosterone therapy causes reappearance of symptoms and reversal of benefits. Lifelong testosterone therapy is therefore recommended for persistent health benefits in most men with testosterone deficiency. Physicians and patients need to be informed of this.