BMI is a statistical calculation intended as an assessment tool. It can be applied to groups of people to determine trends or it can be applied to individuals. When applied to individuals, it is only one of several assessments used to determine health risks related to being underweight, overweight, or obese.
Interpreting BMI calculations for adults
All adults age 20 and older are evaluated on the same BMI scale as follows:
- BMI below 18.5: Underweight
- BMI 18.5-24.9: Normal weight
- BMI 25.0-29.9: Overweight
- BMI 30 and above: Obese
Some researchers consider a BMI of 17 or below an indication of serious, health-threatening malnourishment. In developed countries, a BMI this low in the absence of disease is often an indication anorexia nervosa At the other end of the scale, a BMI of 40 or greater indicates morbid obesity that carries a very high risk of developing obesity-related diseases such as stroke, heart attack, and type 2 diabetes.