Obesity is frequently present in patients with polycystic ovary syndrome (PCOS) and plays an important role in the pathogenesis of the metabolic, endocrine, and reproductive abnormalities associated with this syndrome. We aimed to summarize the effects of lifestyle changes and anti-obesity pharmacotherapy in patients with PCOS. We reviewed the literature regarding the effects of lifestyle changes and anti-obesity agents on the metabolic and endocrine abnormalities of PCOS. Lifestyle changes, including diet, exercise, and behavioral modification, appear to improve the metabolic and reproductive abnormalities of overweight and obese patients with PCOS. Therefore, lifestyle changes appear to represent the first-line management for all overweight and obese patients with PCOS. However, the optimal composition of diet and the optimal type of exercise in these patients are unknown. Anti-obesity agents that have been studied in PCOS include orlistat, sibutramine, and rimonabant. However, the latter two agents have been withdrawn from the market because of side effects. Long-term studies with orlistat in overweight and obese diabetic patients showed greater weight loss and metabolic and cardiovascular benefits than those achieved with lifestyle changes alone. However, there are limited data on the efficacy of orlistat in women with PCOS. In conclusion, lifestyle changes (diet, exercise and behavioral modification), particularly when combined with anti-obesity agents, exert beneficial effects on the endocrine abnormalities of obese patients with PCOS and improve metabolic parameters.