Body Proportionality Index (BPI)

Faculty of Applied Health Sciences




Body Proportionality Index (BPI)

 Authors: Raffy Dotan & Prof. Bareket Falk

The BPI is an upgraded alternative to the widely used Body Mass Index (BMI), aimed at addressing BMI's shortcomings. BPI is valid for ages 5-20 and employs the same ratio format of weight/heightexp used to derive BMI, but replaces the fixed height exponent of 2 by a varying exponent, corresponding to an age- and sex-specific proportionality reference norm. The latter is based on the 50th centile reference values of the U.S. Centers for Disease Control growth charts for height and BMI (Kuczmarski RJ, Ogden CL, Grummer-Strawn LM, et al. CDC Growth Charts: United States Adv Data. 2000;[314]:1-27).

The height exponent is so derived that for any weight and height combination conforming to the reference proportionality for a given age and sex, the BPI value is 10. Consequently, BPI is age- and sex-independent and adiposity can therefore be directly compared between the sexes and across the entire 5-20 age-range. Any need for normalization is thus eliminated. Moreover, unlike BMI, BPI is practically height-independent and is less reflective of body weight. Overall (♂+♀), BPI is similar or marginally better than BMI in reflecting adiposity. It does so better for males and somewhat less so for females.

Unlike BMI, BPI also facilitates direct visualization of the extent of over- or under-weight. Thus, BPI of 13 always denotes 30% over-weight for the given height (+3÷10x100=30%), while a value of 8 would always mean 20% under-weight (-2÷10x100=-20%), regardless of age or sex.

For further information contact Raffy Dotan

Exponent Formula =
A*Age8 –B*Age7 +C*Age6 –D*Age5 +E*Age4 –F*Age3 +G*Age2 –H*Age +I

    Male Female
A 2.906727552*10-7 2.292052619*10-7
B 3.035166037*10-5 2.520048156*10-5
C 1.363688629*10-3 1.199484981*10-3
D 3.446921485*10-2 3.227046481*10-2
E 0.5371033046 0.5363979321
F 5.298140079 5.636552304
G 32.43985307 36.55307788
H 113.3936639 133.901406
I 178.2915843 216.5328255
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