“Studies have shown that the onset of obesity is frequently triggered by behavioral, medical and socioeconomic factors,” says Mary L. Rosser, director of integrated women’s health in the Department of Obstetrics and Gynecology at Columbia University Irving Medical Center in New York City. “Sedentary lifestyle, poor diets, stress, mental health, sleep deprivation, medical issues such as hypothyroidism, PCOS [polycystic ovary syndrome], diabetes and others contribute.”