Your school district now performs annual BMI screenings. Your child brings home a BMI report card which shows that your child has obesity. The child asks what this means. What do you say?
BMI stands for “Body Mass Index” and is an indirect measure of health risk of weight. It is calculated using a person’s height, weight, age and gender. Child/adolescent BMI is a good predictor of health risk into adulthood. So if your child has obesity, he/she has a much higher risk for continuing to have weight problems into adulthood.10
“Some schools use BMI scorecards to inform parents of their child’s weight so that parents and health care professionals can be proactive in addressing any weight-related issues.”
Some schools use BMI scorecards to inform parents of their child’s weight so that parents and health care professionals can be proactive in addressing any weight-related issues. BMI scorecards typically use BMI-for-age which differs from what most adults think of when they think of BMI.
BMI-for-age is a measure of weight compared to growth and, in children, is more accurate than BMI alone. After BMI is calculated for children and teens, the BMI number is plotted on a growth chart (for either girls or boys) to obtain a percentile ranking. Percentiles are the most commonly used indicator to assess the size and growth patterns of individual children in the United States. The percentile indicates the relative position of the child’s BMI number among children of the same sex and age. The growth charts show the weight status categories used with children and teens (underweight, healthy weight, overweight and obese).11
Although the BMI number is calculated the same way for children and adults, the criteria used to interpret the meaning of the BMI number for children and teens are different from those used for adults. For children and teens, BMI age- and sex- specific percentiles are used for two reasons. First, the amount of body fat changes with age. Second, the amount of body fat differs between girls and boys.13