Obesity is a condition of having excess body weight. Adults with a body mass index (BMI, calculated as weight in kilograms divided by height in meters squared) greater than 25 kg/m2 but less than 30 kg/m2 are considered overweight. Adults with a BMI greater than 30 kg/m2 are considered obese.When an adult is more than 100 pounds overweight or has a BMI greater than 40 kg/m2 is considered morbidly obese.

In the U.S., 97 million adults are overweight or obese. Being overweight significantly increases the risk of death from hypertension, dyslipidemia, type 2 diabetes, stroke, osteoarthritis, coronary heart disease, gallbladder disease, sleep apnea and respiratory problems, and endometrial, breast, prostate and colon cancers. Obesity results in an approximate cost of $117 billion in the U.S.

Obesity has reached epic proportions. Rates of obesity have gone up from 12 to 20 percent of the population since 1991. This epidemic is not limited to adults: The percentage of young people who are overweight has more than doubled in the past 20 years. Sixteen percent of children and adolescents between 6 and 19 years old are considered overweight.

Your weight is the result of many factors. These factors include environment, family history and genetics, metabolism (the way your body changes food and oxygen into energy), behavior or habits, and more. You can't change some factors, such as family history. However, you can change other factors, such as your lifestyle habits.

Obesity. Last reviewed 12/31/1969
  • Center for Disease Control
  • National Heart, Lung and Blood Institute
  • National Institutes of Health - National Library of Medicine
  • U.S. Department of Health and Human Services
  • National Institute of Diabetes & Digestive & Kidney Diseases.