Severe obesity is a complex, medical disease, which affects more than four million people in the United States.
A body mass index (BMI) above 40 which usually means at least 100 pounds overweight for men and women indicates that a person is severely obese. Your physician has probably called it morbid obesity. You may calculate your BMI with this formula: weight in pounds x 705 divided by your height in inches and divide that number by your height in inches again.
The result of this calculation is your BMI. People with a BMI of between 35 and 40 who suffer from other medical illnesses can also be classified as suffering from severe or morbid obesity.