Characteristics of obesity in polycystic ovary syndrome: Etiology, treatment, and genetics.

Polycystic ovary syndrome (PCOS) has multiple etiologies including ovarian and adrenal hyperandrogenism, neuro-endocrine and hypothalamic-pituitary dysfunction, and disorders of peripheral insulin resistance. Obesity is neither necessary nor sufficient for the PCOS phenotype, and the association of PCOS with obesity is not universal, with national, cultural, and ethnic differences. Obesity, particularly visceral adiposity which is common in obese and non-obese women with PCOS, amplifies and worsens all metabolic and reproductive outcomes in PCOS. Obesity increases insulin resistance and compensatory hyperinsulinemia, which in turn increases adipogenesis and decreases lipolysis. Obesity sensitizes thecal cells to LH stimulation and amplifies functional ovarian hyperandrogenism by upregulating ovarian androgen production. Obesity increases inflammatory adipokines which, in turn, increase insulin resistance and adipogenesis. Lifestyle interventions focused on diet-weight loss and concurrent exercise are central to therapy which also commonly subsequently needs to include pharmacologic therapy. PCOS symptoms commonly improve with 5% to 10% weight loss, but 25% to 50% weight loss, usually achievable only through bariatric surgery, may be required for morbid obesity unresponsive to lifestyle-medical treatment. Bariatric surgery is a valuable approach to weight loss in PCOS where BMI is ≥40 kg/m2 when non-surgical treatment and/or induction of pregnancy have failed, and can be an initial treatment when BMI is ≥50 kg/m2. Further research in PCOS is needed to better understand the fundamental basis of the disorder, to ameliorate obesity, to correct hyperandrogenism, ovulation, hyperinsulinemia, and to optimize metabolic homeostasis.