Obesity in men has been associated with reduced fertility. The impact of paternal body mass index on fertility is multifactorial, with increased weight associated with endocrine dysregulation and impaired sexual desire and function. Weight loss may improve fertility outcomes as well as conferring longer-term health benefits.
Obesity is a growing health issue that causes substantial morbidity and mortality. Epidemiological data suggest an association between increasing body mass index (BMI) and reduced fertility in men, with one study suggesting that a gain of 10kg decreases male fertility by approximately 10%. The effect of BMI on male fertility is multifactorial, with increased weight associated with changes in sex hormone profile and impaired sexual desire and function. Some studies also suggest poorer semen parameters in overweight men.
Despite the prevalence and costs of male subfertility, there are few data regarding the fertility benefits of weight loss in men. Although weight reduction may normalise the hormone profile, the extent that this improves fertility and the time course of any improvement are unclear.