Most expert opinions and guidelines indicate the necessity for weight loss before in vitro fertilization (IVF) in women who are overweight or obese. This is based on the documented impact of obesity on pregnancy rates and pregnancy complications and the long-term impact on the child in natural conceptions. Some clinicians and authorities refuse to treat patients unless they are below a certain body mass index. In the past this advice has been hindered by a lack of opportunity for patients to join lifestyle programs and the high dropout failure before treatment. However, the ideal has remained in the search for effective methods for weight loss. New clinical trials have evaluated a lifestyle program before IVF treatment and compared the results with those who were merely given advice and allowed to proceed directly to other fertility treatments or IVF. No compelling evidence of the value of lifestyle intervention for weight loss on live-birth rates was gained from these well-conducted studies. The research and medical and ethical opinions may now favor moving to fertility treatment earlier than originally recommended for patients who are overweight or obese.