Obesity can contribute to irregularities in a woman’s menstrual cycle as well as lack of ovulation. However, studies have also shown that even women who ovulate normally but who are severely obese are less likely to become pregnant than women who are normal weight or overweight but not obese.
Obesity can also increase risk of miscarriages and cause complications for both the mother and baby. For a woman who is having difficulty conceiving, even moderate weight loss of just five percent body fat can improve fertility. Weight loss can improve the hormonal environment and restore regular menstruation and ovulation.
In men, obesity has been linked to low testosterone levels and reduced spermatogenesis (sperm production). As with women, weight loss can improve male fertility. Obese men who lose weight may experience an improvement in testosterone levels and sperm production.