Hypogonadism and subfertility can be frequently associated to obesity. These endocrine alterations may have consequences in the health and quality of life of obese men since they may result in impaired fertility and poor sexual life. As many clinical reports suggest, weight loss can ameliorate hypogonadism and, more generally, alterations in sex hormones. This effect is evident even when weight loss is induced by bariatric surgery. The evidence that hypogonadism in morbidly obese patients can regress after bariatric surgery should lead us to consider it as a modifiable comorbidity associated to obesity. This would have as a consequence that obese male patients with symptomatic hypogonadism could be candidates for bariatric surgery even with a BMI < 40 kg/m(2). Controlled clinical trials, involving obese hypogonadal males, should be encouraged.