Obesity is currently one of the most serious public health problems which affects up to 30-40% of the population, and its prevalence is higher in men than in women. Complications of obesity include atherosclerosis, cardiovascular diseases, and type 2 diabetes mellitus, but it also has a negative impact on the hormonal system and fertility. The hormonal consequences of excess body fat in men are functional hypogonadism, which not only causes clinical symptoms of testosterone deficiency, but is also a risk factor for obesity (a vicious circle mechanism). Reduced fertility in obese men may be a consequence of functional hypogonadotropic hypogonadism (decreased gonadotropins and testosterone secretion, reduced libido, and erectile dysfunction), but other mechanisms associated with excess adipose tissue, like hyperinsulinaemia, hyperleptinaemia, chronic inflammation, and oxidative stress also play an important role. Therefore, in obese men deterioration of semen parameters (sperm concentration, motility, and morphology) and reduced fertility are observed, also concerning the effectiveness of assisted reproductive techniques. Reducing the mass of adipose tissue causes an increase in testosterone concentrations and has a beneficial effect on semen parameters. Functional hypogonadism in obese men should be diagnosed only after exclusion of organic causes of hypogonadism. Lifestyle changes, including physical exercise and low-caloric diet, and optimization of comorbidities, are still first line of treatment. In some patients, if such treatment is ineffective, pharmacotherapy or bariatric surgery may be considered. Testosterone replacement therapy is contraindicated in obese men with functional hypogonadism, especially in those who desire fertility. Selective oestrogen receptor modulators and aromatase inhibitors improve sperm quality but are not recommended for the treatment of hypogonadism in obese men. GLP-1 analogues appear to be effective and safe in the treatment of low testosterone and infertility in obese men and may be the main method of pharmacotherapy in the future.
Keywords: GLP-1 analogues; bariatric surgery; hypogonadism; infertility; men; obesity; testosterone replacement therapy.