### Description

Weststrate and Deurenberg proposed an equation of estimating the percent body fat in children from body density. This is more accurate than the Siri equation in this population.

Parameters:

(1) age in months if < 2 years old and in years if >= 2 years old

(2) body density in kg per L

percent body fat for boys and girls < 2 years of age =

= ((585 - (4.7 * ((age in months)^0.5))) / (density)) - (550 - (5.1 * ((age in months)^0.5)))

percent body fat for boys 2 to 18 years of age =

= ((562 - (4.2 * ((age in years) - 2))) / (density)) - (525 - (4.7 * ((age in years) - 2)))

percent body fat for girls 2 to 10 years of age =

= ((562 - (1.1 * ((age in years) - 2))) / (density)) - (525 - (1.4 * ((age in years) - 2)))

percent body fat for girls 10 to 18 years of age =

= ((553 - (7.3 * ((age in years) - 10))) / (density)) - (514 - (8.0 * ((age in years) - 10)))

Performance:

• The Siri equation uses 1.1 kg/L as the density for fat-free mass. This results in an overestimation of the body fat in children.

• The Weststrate and Deurenberg method assumes that the density of fat-free mass increases during childhood.