A dramatic change in body weight, either weight gain or weight loss, can lead to reduced fertility in men as well as women. However, the effect of weight on male fertility is not as pronounced as it is in women. Ultimately, the possible effect of a man’s bodyweight on his fertility will depend on the original quality of his sperm. However a healthy lifestyle is desirable in all cases.

Body fat influences the production of gonadotropin releasing hormone (GnRH), which is essential for sperm production in men. GnRH specifically activates the secretion of luteinizing hormone (LH) and follicle stimulating hormone (FSH), both of which are essential for the development of sperm.