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### Body Mass Index

Body mass index, commonly referred to as BMI, is a way to assess a person’s tissue mass, including bone, muscle, and fat. It is used for both men and women, but variations exist for children, and normative ranges can vary depending on a person’s race. Both high and low BMI values have important health implications. This entry first explains how to calculate BMI and how it is used; then, limitations and alternatives to BMI are presented, followed by the implications of BMI results and, finally, its use in children.

### Formula

BMI is calculated by measuring one’s weight in kilograms divided by one’s height in meters squared:

$\begin{array}{c}\text{BMI}=\text{weight}\text{\hspace{0.17em}}\left(\text{kg}\right)\\ {\text{height}}^{2}\text{\hspace{0.17em}}\left({\text{m}}^{2}\right)\end{array}$

In the United States, height and weight are regularly measured in pounds and feet, respectively; thus, the values must be converted to ... • • • 