Various methods are used to determine if someone’s
weight has increased his or her health risks. Some are based on the relationship
between height and weight; others are based on measurements of body fat. The
most commonly used method today is the body mass index (BMI). BMI is an index of
weight adjusted for the height of an individual.
BMI can be used to screen for both overweight and
obesity in adults. It is the measurement of choice for many obesity researchers
and other health professionals, as well as the definition used in most published
information on overweight and obesity. BMI is a calculation based on height and
weight, and it is not gender-specific in adults. BMI does not directly measure
percentage of body fat, but it is a more accurate indicator of overweight and
obesity than relying on weight alone.
BMI is calculated by
dividing a person’s weight in kilograms by height in meters squared. The
mathematical formula is “weight (kg)/height (m˛).”
To determine BMI using pounds and inches,
multiply weight in pounds by 704.5,* divide the result by height in inches, and
then divide that result by height in inches a second time. (You can also use the
BMI calculator at www.nhlbisupport.com/bmi or check the chart
* The multiplier 704.5 is used by the National Institutes of Health (NIH).
Other organizations may use a slightly different multiplier; for example, the
American Dietetic Association suggests multiplying by 700. The variation in
outcome (a few tenths) is insignificant.