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Facts about body mass index

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What does BMI tell you?
Body mass index (BMI) is a single number that evaluates an individual’s weight status in relation to his or her height. BMI generally is used as the first indicator in assessing body fat and has been the most common method of tracking weight problems and obesity among adults. Although this is an effective screening tool for children and adolescents, it is important to remember that it is not a diagnostic tool.

BMI provides a guideline based on weight and height to determine weight issues. As children grow, their body fat changes. BMI decreases during the preschool years, then increases as the child grows older. This pattern is shown better on the BMI-for-age charts. BMI-for-age charts are recommended to assess weight in relation to stature for older children (2 years to 20 years).

What are the advantages of using BMI?

• BMI-for-age can be used for adolescents beyond puberty.

• BMI in children and adolescents compares well to laboratory measures of body fat and weight-for-stature measurements.

• BMI is related to health risk, such as cardiovascular disease, hyperlipidemia, elevated insulin, and increased blood pressure.

• BMI makes it easier to track childhood obesity into adulthood.

Body Mass Index formula
Two methods are used to calculate BMI – the metric formula and the English formula. Both provide the same information, and neither is more accurate than the other.

Metric Formula
BMI = Weight in kilograms / [Height in meters] x 2
or
BMI = [Weight in kilograms / Height in cm / Height in cm] x 10,000

English Formula
BMI = [Weight in pounds / Height in inches / Height in inches] x 703

How to determine BMI for age
The guidelines for interpreting BMI are listed below. It is critical that accurate measurements are obtained. It is common for caregivers to be concerned about their child’s weight and where he or she is on the growth chart.

• Underweight BMI-for-age < 5th percentile

• At risk of overweight BMI-for-age > 85th percentile

• Overweight BMI-for-age > 95th percentile

For additional information, visit http://www.keepkidshealthy.com/welcome/bmicalculator.html