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 Overweight and Obesity
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Defining Childhood Overweight

photo of a scale with feetBody mass index (BMI) is a practical measure used to determine overweight. BMI is a measure of weight in relation to height that is used to determine weight status. BMI can be calculated using either English or metric units. BMI is the most widely accepted method used to screen for overweight in children and adolescents because it is relatively easy to obtain the height and weight measurements needed to calculate BMI, measurements are non-invasive and BMI correlates with body fatness.6 While BMI is an accepted screening tool for the initial assessment of body fatness in children and adolescents, it is not a diagnostic measure because BMI is not a direct measure of body fatness.


Use of BMI to Screen for Overweight in Children

For children and adolescents (aged 2–19 years), the result is plotted on the CDC growth charts to determine the corresponding BMI-for-age percentile. Overweight is defined as a BMI at or above the 95th percentile for children of the same age and sex. This definition is based on the 2000 CDC Growth Charts for the United States.7 A child’s weight status is determined based on an age- and sex-specific percentile for BMI rather than by the BMI categories used for adults. Classifications of overweight for children and adolescents are age- and sex-specific because children’s body composition varies as they age and varies between boys and girls.

For more information, see the About BMI for Children and Teens.

Tips for Parents
What can you do as a parent or guardian to help prevent childhood overweight? We have some ideas in our Healthy Weight section.

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Page last reviewed: May 22, 2007
Page last updated: May 21, 2008
Content Source: Division of Nutrition, Physical Activity and Obesity, National Center for Chronic Disease Prevention and Health Promotion