Using the growth chart, your doctor determines your child's percentile, meaning how your child compares to other children of the same sex and age. So, for example, you might be told that your child is in the 80th percentile. This means that compared with other children of the same sex and age, 80 percent have a lower BMI.

Cutoff points on these growth charts, established by the Centers for Disease Control and Prevention (CDC), help identify overweight children:

• BMI-for-age between 85th and 95th percentiles — at risk of overweight
• BMI-for-age over 95th percentile — overweight

Because BMI doesn't consider things like being muscular or having a larger-than-average body frame and because growth patterns vary greatly among children, your doctor also factors your child's growth and development into the overall weight assessment. This helps determine whether your child's weight is a health concern.

In addition to BMI and charting weight on the growth charts, the doctor also evaluates:

• Your family's history of obesity and weight-related health problems, such as diabetes
• Your child's eating habits and calorie intake
• Your child's activity level
• Other health conditions your child may have