METHOD AND APPARATUS FOR MEASURING BODY FAT PERCENTAGE

摘要

The body fat percentage (%fat) is determined by the Brozek's or Siri's approximation (1) of a function of the body density D: %fat = [( alpha /D) - beta ] x 100, where alpha = 4.570 and beta = 4.142 in the Brozek's formula and alpha = 4.950 and beta = 4.500 in the Siri's formula. A subject enters a water tank (1) with his head portion (5) kept outside the water surface (6) and assumes a maximum exbreath state. Under this state, the body weight of the subject below the water surface or a fluid substitution quantity is measured so as to determine the apparent volume Va of the subject. Next, the body volume Vs of the subject other than the head portion is obtained by subtracting the residual air quantity of the subject, which is calculated separately, from the apparent volume Va. At least two of the circumferences of the head and the neck, the width of the head and the lengths of the face and the head are measured, and the head volume Vh is estimated by calculating a predetermined multiple recurrence formula or conducting image analysis. The body density is calculated approximately by dividing the body weight W of the subject in the air by the whole body volume obtained by adding the volume Vs of the body portion and the volume Vh of the head portion, and the "D" value thus obtained is substituted in the approximation (1) given above to determine the body fat percentage.