You may be hearing this new abbreviation the next time you bring your child in for a check-up. Although we doubt it will become as popular as your astrological sign, everyone has a BMI.

Body Mass Index (or BMI) is a measurement of a person's weight compared to his or her height. The BMI is calculated using a simple formula and is considered a reliable indicator of body fat. BMI has been used in adults for some time to assist in defining a "healthy" weight. A BMI score of approximately 18 to 25 is generally considered an indication of a "healthy" adult weight for both men and women.

In recent years, as obesity has become a larger problem in the pediatric population, clinicians have begun using BMI measurement as an additional health assessment tool with children. Unlike the adult, a “healthy" BMI for a child varies with age and gender.

While BMI measurement is helpful, it does have a couple of limitations.
• BMI may overestimate fatness in individuals who have a very muscular build—such as the elite athlete.
• BMI also may underestimate fatness in individuals who have lost muscle mass for some reason or other.

Children will have lower BMI cut-off for being overweight and obese (go to www.pediatrics.about.com to calculate your child’s BMI).

—Roxanna Plough, CPNP