What are causes of obesity?

30% genetic predisposition, but environment is major factor determining expression of obesity. Secondary causes (hypothyroid, Cushing's, insulinoma, PCOS, hypothalamic obesity, GH deficiency, OCP, meds (phenothiazine, valproate, carbamazepine, antidepressants, cortisol, insulin), eating disorders (binge-eating, bulimia nervosa, night-eating) hypogonadism, pseudohypoparathyroid, obesity of tube feeding.