| BMI - Body Mass Index: BMI for Children
and Teens (BMI for
Children and Teens is sometimes referred to as "BMI-for-age.")
BMI is Used Differently with Children Than it is With Adults
In children and teens, body mass index is used to assess underweight,
overweight, and risk for overweight. Children's body fatness changes
over the years as they grow. Also, girls and boys differ in their
body fatness as they mature. This is why BMI for children, also
referred to as BMI-for-age, is gender and age specific.1, 2 BMI-for-age
is plotted on gender specific growth charts. These charts are
used for children and teens 2 – 20 years of age. For the
2000 CDC Growth Charts and Additional Information visit CDC's
National Center for Health Statistics.
Each of the CDC BMI-for-age gender specific charts contains a
series of curved lines indicating specific percentiles. Healthcare
professionals use the following established percentile cutoff
points to identify underweight and overweight in children.
Underweight BMI-for-age < 5thpercentile
Normal BMI-for-age 5th percentile to < 85th percentile
At risk of overweight BMI-for-age 85th percentile
to < 95th percentile
Overweight BMI-for-age > 95th percentile
BMI decreases during the preschool years, then increases into
adulthood. The percentile curves show this pattern of growth.
What does it mean if my child is in the 60th percentile?
The 60th percentile means that compared to children of the same
gender and age, 60% have a lower BMI.
Example
Let's look at the BMI for a boy as he grows. While his BMI changes,
he remains at the 95th percentile BMI-for-age.
Age BMI Percentile
2 years 19.3 95th
4 years 17.8 95th
9 years 21.0 95th
13 years 25.1 95th
We see how the boy's BMI declines during his preschool years
and increases as he gets older.
Why is BMI-for-age a useful tool?
BMI-for-Age is used for children and teens because of their rate
of growth and development. It is a useful tool because
BMI-for-age provides a reference for adolescents that can be
used beyond puberty.
BMI-for-age in children and adolescents compares well to laboratory
measures of body fat.
BMI-for-age can be used to track body size throughout life.
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