The prevalence of overweight and obesity in women of reproductive age has increased over the past 30 years. Infertility affects 1 in 7 couples, and female obesity is associated with anovulation. The mechanisms by which excessive fat delays time to pregnancy (TTP) appear rooted in ovulatory problems and direct effects on oocytes, causing poorer embryo development, as well as in effects on the endometrium. Weight loss in women has been shown to improve conception, but not necessarily live birth rates following fertility treatment, and further research in this area is needed. The obesity epidemic has been accompanied by a potential rise in male infertility, which has been attributed to hormonal disturbances and compromised semen parameters.