The Body Mass Index

Defining “BMI”

The Body Mass Index (BMI) is a simple formula that assesses our weight relative to our height. It is an indirect measure of body composition because it correlates highly with body fat. BMI has some limitations; it can overestimate body fat in persons who are very muscular, and it can underestimate body fat in persons who have lost muscle mass, such as many elderly.

Why check your BMI?

Keeping your weight within the healthy guidelines established in the body mass index will help reduce your risk of illnesses such as heart disease, stroke, high blood pressure (hypertension) and type II diabetes.

According to the Surgeon General’s report in 2001 (The Surgeon General's Call To Action To Prevent and Decrease Overweight and Obesity Economic Consequences), people who are overweight and their associated health problems have substantial economic consequences for the United States health care system. In 1995, the total (direct and indirect) costs attributable to obesity amounted to an estimated $99 billion. In 2000, the total cost of obesity was estimated to be $117 billion. Most of the cost associated with obesity is due to type II diabetes, coronary heart disease, and hypertension. The costs rise with every passing year.

The following chart reflects the categories associated with BMI ranges for adults:

Now take a look at the BMI chart below and see where you are:

(The American Heart Association)

Interpretation of BMI categories for adults is not dependent on sex or age; however, for children and teenagers, they are dependent on sex or age because the amount of body fat changes from birth to approximately age twenty. Another factor is that the amount of body fat differs between girls and boys. To check the BMI for children and teenagers, click on the following link:

http://apps.nccd.cdc.gov/dnpabmi/Calculator.aspx

The simplicity of this method is appealing to Health and Physical Education teachers throughout the country and is being incorporated into more school programs every year. For school districts using the Fitness Education Curriculum Model, utilizing the Body Mass Index is an important tool for assessment within every fitness unit. Used in conjunction with its youth fitness partner, PHYSICAL BEST and FITNESSGRAM, the BMI is part of a complete fitness education program demonstrating increased accountability that marks an important step toward lowering childhood obesity rates.

Sources: The American Heart Association. The World Health Organization. The Center For Disease Control and Prevention. National Center for Health Statistics in collaboration with the National Center for Chronic Disease Prevention and Health Promotion (2000). The Cooper Institute, 2007.