Body Mass Index - BMI

Body mass index or BMI (wt/ht²) is measure of body fat based on height and weight that applies to both adult men and women. For adults over 20 years old, BMI falls into one of these categories:

The BMI ranges are based on the effect body weight has on disease. As BMI increases, the risk for some diseases increases. Some common conditions related to overweight and obesity are:

• Cardiovascular disease
• High blood pressure
• Osteoarthritis
• Some cancers
• Diabetes
• Premature death

BMI is only one of the many factors which are used to predict the risk of getting a disease. We have to remember that weight is only one factor that is related to disease.

BMI For Children And Teens

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. BMI-for-age is plotted on gender specific growth charts. These charts are used for children and teens 2 – 20 years of age.

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.

Percentile	Weight Status
BMI-for-age < 5th percentile	Underweight
BMI-for-age 85th percentile to < 95th percentile	Overweight
BMI-for-age > 95th percentile	Obese

What does it mean if my child is in the 70th percentile? The 70th percentile means that compared to children of the same gender and age, 70% have a lower BMI.

BMI decreases during the preschool years, then increases into adulthood. The percentile curves show this pattern of growth.

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.

What are the advantages of using BMI-for-age with children from 2 to 20 years? BMI-for-age provides a reference for adolescents that can be used beyond puberty. BMI in children and adolescents compares well to laboratory measures of body fat. BMI-for-age can be used to track body size throughout life. Children with a BMI-for-age above the 95th percentile are more likely to become overweight adults.

Content Source: www.cdc.gov

For more information on how to use the growth charts visit
The Growth Chart Training Modules.

For the 2000 CDC Growth Charts and Additional Information visit CDC'S
National Center for Health Statistics

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