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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 ...