According to the National Institutes of Health, anyone weighing 20% or more than the ideal for his or her body is obese. At that point, the extra weight becomes a health risk, contributing to a number of conditions – many of them life-threatening.
One way to determine whether you are obese is by calculating your Body Mass Index (BMI). An individual whose BMI is in the 25-29.9 range is considered overweight. A BMI of 30 or higher signals obesity. A BMI of 40 or greater is considered morbidly obese, or obesity at a level significant enough to be life-threatening.