What causes obesity in adults?

BY A STAFF REPORTER: Several factors can play a role in gaining and maintaining excess weight. People gain weight when they burn more calories than they burn through physical activity. Scientists believe that genes may increase the likelihood of obesity, but external factors such as abundant food or low physical activity may also be necessary for a person to become overweight. Some drugs can also cause weight gain, including some corticosteroids, antidepressants, and anticonvulsants. Studies have shown that the less sleep you get, the more likely you are to be overweight or obese.