Although there are genetic, behavioral and hormonal influences on body weight, obesity occurs when you take in more calories than you burn through exercise and normal daily activities. Your body stores these excess calories as fat.

Obesity can sometimes be traced to a medical cause, such as Prader-Willi syndrome, Cushing's syndrome, and other diseases and conditions. However, these disorders are rare and, in general, the principal causes of obesity are:

  • Inactivity. If you're not very active, you don't burn as many calories. With a sedentary lifestyle, you can easily take in more calories every day than you use through exercise and normal daily activities.
  • Unhealthy diet and eating habits. Weight gain is inevitable if you regularly eat more calories than you burn. And most Americans' diets are too high in calories and are full of fast food and high-calorie beverages.
June 10, 2015