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BMI for Children and Teens
(Also 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.
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Underweight |
BMI-for-age < 5th percentile
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At risk of overweight |
BMI-for-age 85th percentile
to < 95th percentile
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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. |
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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 |
95 th |
| 4 years |
17.8 |
95 th |
| 9 years |
21.0 |
95 th |
| 13 years |
25.1 |
95 th |
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.
References
1 Hammer LD, Kraemer HC, Wilson DM, Ritter PL, Dornbusch SM. Standardized
percentile curves of body-mass index for children and adolescents. American
Journal of Disease of Child . 1991; 145:259-263.
2 Pietrobelli A, Faith MS, Allison DB, Gallagher D, Chiumello G, Heymsfield,
SB. Body mass index as a measure of adiposity among children and adolescents:
A validation study. Journal of Pediatrics . 1998; 132:204-210.
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