Male hypogonadism in overweight and obesity

Obesity-related gonadal dysfunction in males has been defined recently as male obesity secondary hypogonadism (MOSH). Affected individuals present with signs and symptoms related to the sex hormone imbalance but also with a burden of metabolic risk factors and occasionally compromised fertility. In pathophysiological terms, excess body fat is associated with leptin and insulin resistance. Accelerated synthesis of leptin and hyperinsulinemia downregulate the expression of kisspeptin receptors and, consequently, the action of kisspeptin. This critical neuropeptide is known to control gonadotropin secretion. In obese males, enhanced activity of the aromatase enzyme is associated with an increase in the conversion of circulating testosterone to estrogen, further promoting a state of hypogonadism. In addition, high fat and low fiber intake alter the intestinal microbiome and the dysfunction of the gut-brain axis. Weight loss appears to be the key to readjusting the function of the hypothalamus-pituitary-gonadal axis. It can be achieved with lifestyle measures in combination with weight loss medications or bariatric surgery. The degree of weight loss appears to resolve the symptoms related to hypogonadism and improve fertility chances. However, the role of hormone replacement is also important, as testosterone replacement has been shown to reduce fat mass and increase the amount of lean body mass while also contributing to weight loss and the regulation of body mass index and waist circumference. This narrative review analyzes the evidence on developing obesity-related endocrinopathies and the available management options. Further research is required to estimate the cut-off of body mass index associated with a higher risk for hypogonadism.