Infertility affects men to almost the same extent as women.
The impact of excess body mass on the endocrine factors that negatively correlate with fertility has been well documented. Overweight in men is directly related to increased oestrogen production in the adipose (fatty) tissue and reduced production of androgens (the so-called male hormones), including testosterone and sex hormone binding globulin (SHBG). Excessive levels of oestrogen in men may disturb the process of spermatogenesis, i.e. the formation of new spermatozoa. Due to the fact that the less testosterone there is, the more fat is accumulated, especially in the abdominal area, overweight and obesity also have a negative effect on sexual functions and may be the underlying cause of erectile dysfunctions.
Some research suggests a negative impact of increased BMI on semen parameters.
Excessive amounts of abdominal fat lead to increased testicular temperature whereas high temperatures in the scrotum translate into poor semen quality. Obesity may reduce the number of spermatozoa with proper structure and progressive motion.
The meta-analysis of twenty one examinations (Sermondade et al.), encompassing a total of more than thirteen thousand male subjects, demonstrated that overweight and obesity were correlated with a more frequent incidence of oligozoospermia (a lower than normal number of spermatozoa – total or per 1 ml of ejaculate) or azoospermia (a lack of spermatozoa in a semen sample).
Due to such a negative impact of overweight on male fertility, men who plan to become fathers are recommended to go on a diet combined with physical activity and dietary supplementation to provide the body with proper nutrients.