Causes of Obesity
Genetic, environmental, psychological and other factors all may play a role in obesity, which occurs when a person's calorie intake exceeds the amount of energy he or she burns.

Genetic factors Obesity tends to run in families, but since family members share diet and lifestyle habits as well as genes, identifying genetics as the sole cause may be difficult. Many people genetically predisposed to obesity do not become obese or manage to lose the weight and keep it off.

Environmental factors Environmental factors include lifestyle behaviors, such as diet and activity levels.

Psychological factors Many people eat in response to negative emotions, such as boredom, sadness or anger. Most overweight people have no more psychological disturbance than normal weight people, but about 30 percent of people seeking treatment for serious weight problems have trouble with binge eating. Binge eaters consume large amounts of food while feeling they can't control how much they are eating.

Other causes Some illnesses, including hypothyroidism, Cushing's syndrome, depression and certain neurological problems can lead to overeating. Certain drugs, such as steroids and some antidepressants, may cause excessive weight gain. A doctor can make the diagnosis in these cases, which are believed to be responsible for only about one percent of all obesity cases.