The impact of obesity on the male reproductive axis.

Obesity, defined as a body mass index (BMI) >30 kg/m2, has seen an important increase in prevalence in the last decades, not only in Europe and the United States, but also in developing countries. It is an established risk factor for numerous pathologic conditions like diabetes mellitus, cardiovascular diseases and cancer, but has also been linked to male hypogonadism. Several studies showed a negative impact of excessive BMI on testosterone levels, sexual function and sperm parameters. Possible mechanisms beyond this phenomenon are reduced hypothalamic and pituitary secretory function, excess estrogen production and reduced circulating sex-hormone binding globulin (SHBG). Peptides produced by the adipocyte may also trigger modifications of the reproductive function. Independently of the method used, non-surgical approach or bariatric techniques, weight reduction and a return to a normal BMI have been associated with improvement in the sexual function and levels of sexual hormones in obese males, showing that obesity related hypogonadism is preventable. Sexual and reproductive health might represent additional motivational factors for men in order to maintain a healthy life-style.