The FIT-PLESE study includes three phases: lifestyle intervention, infertility treatment, and pregnancy. Phase I will involve randomization to either an Intensive Lifestyle Modification program or a Standard Physical Activity Program. The Intensive Lifestyle Modification Program will consist of an over the counter weight loss drug (Orlistat/Alli), caloric restriction assisted by the use of meal replacements (Nutrisystem), and increased physical activity (monitored by a Fitbit). The Standard Physical Activity Program will consist of increased physical activity alone (monitored by a Fitbit). After completion of the 16 week lifestyle intervention, subjects will receive up to 3 cycles of ovarian stimulation with an oral medication (clomiphene citrate), triggered ovulation with hCG, and a single intrauterine insemination per cycle (Phase II). Subjects who conceive in either Phase I or Phase II will have visits once per trimester and all pregnancies will be followed to completion (Phase III). Participation in this study may take up to 18 months to complete, and may require an average of 17 study-related visits.