Metabolic disturbances are common in women with polycystic ovary syndrome (PCOS). Obesity is the major link in the association of PCOS with diabetes, metabolic syndrome, hypertension, low-grade chronic inflammation and increased body iron stores, among others. Metabolic prevention in PCOS women should start as early as possible, usually meaning at diagnosis. Among preventive strategies, those promoting a healthy life-style based on diet, regular exercising and smoking cessation are possibly the most effective therapies, but also are the most difficult to achieve. To this regard, every effort must be made to avoid weight gain and obesity, given the deleterious impact that obesity exerts on the metabolic and cardiovascular associations of PCOS. Unfortunately, classic strategies that address obesity by life-style modification and dieting are seldom successful on a long-term basis, especially in women with severe obesity. In selected cases, metabolic surgery in severely obese women may resolve signs and symptoms of PCOS restoring insulin sensitivity and fertility, and avoiding the long-term risks associated with PCOS and morbid obesity. Surgical techniques for bariatric surgery have evolved in the past decades and newer procedures do not longer carry the severe side effects associated with earlier bariatric procedures. The choice of bariatric procedure should consider both the severity of obesity and the possibility of future pregnancy, since fertility may be restored by the sustained and marked weight loss usually attained after bariatric surgery. Finally, avoidance of the risks associated with morbid obesity compensate for the possible residual risks for pregnancy derived from the previous bariatric procedure itself.