Diagnosis

As part of regular well-child care, the doctor calculates your child's BMI and determines where it falls on the BMI-for-age growth chart. The BMI helps indicate if your child is overweight for his or her age and height.

Using the growth chart, your doctor determines your child's percentile, meaning how your child compares with other children of the same sex and age. For example, if your child is in the 80th percentile, it means that compared with other children of the same sex and age, 80% have a lower BMI.

Cutoff points on these growth charts, established by the Centers for Disease Control and Prevention, help classify the severity of a child's weight problem:

• BMI between 85th and 94th percentiles — overweight
• BMI 95th percentile or above — obesity
• BMI 99th percentile or higher — severe obesity

Because BMI doesn't consider things such as being muscular or having a larger than average body frame and because growth patterns vary greatly among children, your doctor also factors in your child's growth and development. 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 evaluates:

• Your family's history of obesity and weight-related health problems, such as diabetes
• Your child's eating habits
• Your child's activity level
• Other health conditions your child has
• Psychosocial history, including incidences of depression, sleep disturbances, and sadness and whether your child feels isolated or alone or is the target of bullying

Blood tests

Your child's doctor might order blood tests that may include:

• A cholesterol test
• A blood sugar test
• Other blood tests to check for hormone imbalances or other conditions associated with obesity

Some of these tests require that your child not eat or drink anything before the test. Ask if your child needs to fast before a blood test and for how long.