Obesity is defined as having a body mass index (BMI) of 30 or greater.
There is a subset of obesity called morbid or extreme obesity which is defined as having a BMI of 40 or greater or weighing in excess of 100 pounds of one’s ideal weight. The National Center for Health Statistics does not track that number.
However several of our scientists, writing in the Journal of the American Medical Association (JAMA) do report on this particular condition. For the period 2003-2004 almost 5 percent of adults were extremely obese.