The Bottom Line on BMI “body mass index”

from Shine Newsletter, Summer 2007

“There’s no magic number when it comes to your child’s weight, because not all children have the same body type or develop at the same rate — even if they’re the same gender, height and age,” said Marilyn Day, MS, RD, co-director of The Children’s Hospital Heart Institute preventive programs. “However, a BMI chart can help gauge whether your child has body fat levels that place him at higher risk for developing health conditions such as diabetes and heart disease.”

Follow these steps to get information on your child’s weight:

• Ask a doctor. Older children and teens with higher-percentile BMIs are more likely to have weight problems and associated health conditions as adults. Children with a high BMI also can face health problems prior to adulthood. However, a child can have a high BMI due to a large frame or a lot of muscle rather than excess fat, so a measurement of body composition is helpful. 
• Do the math. To calculate your child’s BMI, use the simple equation below. Then plot your child’s BMI on a BMI-for-age growth chart. Your child falls into a healthy percentile range if he is between the fifth and 85th percentile.

Weight (in pounds) / Height (in inches)2  = _______ Number from above_______ x 703 = BMI.

• Watch the curve . BMI measurements fluctuate as your child grows, so they’re more reliable when you view them over time. Your child’s pediatrician or family doctor  can assess whether your child’s weight and growth patterns are indeed healthy.