Polycystic ovary syndrome (PCOS) and obesity are common and complicated disorders that are influenced by genetic and environmental factors. Obesity is a prominent feature of PCOS; at least 50% of patients with PCOS are obese. Obesity appears to exert an additive, synergistic effect on the manifestations of PCOS, independently impacting insulin sensitivity, risk for diabetes, and adverse cardiovascular profile. There is evidence for the benefit of weight reduction in the management of PCOS in the obese patient. Weight loss remains a primary intervention in treatment of this disorder.