Stratify by BMI Percentile

Visual inspection is a poor method for clinicians to use to recognize obesity. The recommended method is calculation of the BMI. The BMI is a measure of body weight adjusted for height used for children > 2 years of age (for children < 2 years of age use weight-for-length). BMI = weight (in kilograms) divided by the square of height (in meters). It is easy to perform in the office setting and recommended over skin-fold thickness, waist circumference, and DEXA.

BMI Calculator  

BMI levels have been shown to correlate with body fat (especially at higher BMI values) and concurrent health risks, especially cardiovascular risk factors. High BMI predicts future adiposity, as well as future morbidity and death. In children, since they are constantly growing and developing, BMI percentiles specific to age and sex are used to determine cut points.

BMI does have limitations in its ability to assess adiposity in distinguishing between fat mass and lean body mass (e.g., Football player who appears overweight but is not overfat). On the other hand, someone with decreased lean body mass and increased adiposity may be misclassified by BMI assessment. BMI may also differ across ethnicity, such that risk of comorbidities may be present at lower BMI thresholds. Clinicians must use their judgment, after assessment of each individual child’s health, family and medical history, BMI trajectory, diet and activity habits, in choosing appropriate language that will convey concern with an empathetic, nonjudgmental approach. Some families will be offended by the word, "obese," but may respond better to terms such as "excess weight" or "elevated BMI."