How do you know if your child is overweight or obese?

Learn to use the Body Mass Index (BMI). Like we mentioned before, the easiest way is to do a simple calculation and determine your child’s Body Mass Index (BMI). However, there are some caveats, which are outlined here.

Why can’t healthy weight ranges be provided for children and teens?

Healthy weight ranges cannot be provided for children and teens for the following reasons:

• Healthy weight ranges change with each month of age for each sex.

• Healthy weight ranges change as height increases.

How can I tell if my child is overweight or obese?

CDC and the American Academy of Pediatrics (AAP) recommend the use of the Body Mass Index (BMI) to screen for overweight and obesity in children and teens aged 2 through 19 years. Although the body mass index is used to screen for overweight and obesity in children and teens, BMI is not a diagnostic tool.

For example, a child who is relatively heavy may have a high BMI for his or her age. To determine whether the child has excess fat, further assessment would be needed. Further assessment might include skin fold thickness measurements, or hydrostatic body fat testing. To determine a counseling strategy, assessments of diet, health, and physical activity are needed. Consult your physician.

Can I determine if my child or teen is obese by using an adult BMI calculator?

No. The adult calculator provides only the BMI number and not the BMI age- and sex-specific percentile that is used to interpret BMI and determine the weight category for children and teens. It is not appropriate to use the BMI categories for adults to interpret BMI numbers for children and teens.

My two children have the same BMI values, but one is considered obese and the other is not. Why is that?

The interpretation of BMI-for-age varies by age and sex so if the children are not exactly the same age and of the same sex, the BMI numbers have different meanings. Calculating BMI-for-age for children of different ages and sexes may yield the same numeric result, but that number will fall at a different percentile for each child for one or both of the following reasons:

• The normal BMI-related changes that take place as children age and as growth occurs.

• The normal BMI-related differences between sexes.

See the following graphic for an example for a 10-year-old boy and a 15-year-old boy who both have a BMI-for-age of 23. (Note that two children of different ages are plotted on the same growth chart to illustrate a point. Normally the measurement for only one child is plotted on a growth chart.)

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