What Is the BMI?

The BMI (Body Mass Index) is a tool for understanding obesity and its use in children is growing. Your pediatrician has probably used it at your child’s annual check-up and you may have seen it used in the school setting soon.

But what is it exactly?

The BMI is an assessment tool that looks at the relationship of weight and height, determining the status of a person’s body weight for their current height.  The BMI calculation will classify an individual as underweight, healthy weight, overweight, or obese.

The BMI is a screening tool that was developed for populations to determine public health risk for chronic diseases such as heart disease and diabetes. Its use in children over the age of two has increased over the years due to the rising incidence of childhood obesity. Most pediatricians are routinely assessing the BMI at your child’s annual check-up.

The best thing about the BMI measurement is it can help you see trends in your child’s growth and allow early intervention if needed. Normally, children grow along a self-established channel and curve. If there is a sudden jump up on the BMI growth curve, this may indicate your child is picking up extra weight. If there is a drop on the curve, weight loss may be a concern.

The BMI measurement has its limitations. For example, the BMI provides a total body index and does not differentiate body frame size and muscle mass from fat stores.  In other words, you may have a large-framed child that is muscular who may be classified as overweight or obese.  Looking at children as individuals including what they eat, how they eat, how physically active they are, and the parents’ frame size can help keep the right perspective when it comes to your child’s weight and interpreting his BMI result.

If you are told your child’s BMI is too high, consult with your pediatrician, registered dietitian, or other health care provider to gather information and education that is tailored to your child, family, and lifestyle.  An elevated BMI and the associated risks for chronic disease can be normalized and/or reversed with healthy eating, physical activity, and lifestyle changes.  For a BMI calculator tool, go to http://apps.nccd.cdc.gov/dnpabmi/.