TITLE:
Measuring obesity: results are poles apart obtained by BMI and bio-electrical impedance analysis
AUTHORS:
Rashee Mittal, Madhur M. Goyal, Raju C. Dasude, Syed Zahiruddin Quazi, Anjan Basak
KEYWORDS:
Obesity; BMI; Bioelectrical Impedance Analysis
JOURNAL NAME:
Journal of Biomedical Science and Engineering,
Vol.4 No.11,
November
17,
2011
ABSTRACT: Objective: To analyse the use of BMI and bioelectrical impedance analysis (BIA) in assessment of adiposity among young and elderly population. Materials and methods: Age, height, weight and percent body fat (PBF) of 101 young and 276 elder subjects were recorded. PBF was measured directly by BIA instrument (PBFb) and also calculated from BMI (PBFf). The classification of subjects into underweight, normal, overweight and obese was based on the age- and sex-specific BMI cutoff values and PBFb following standard guidelines. Results: The calculated mean BMI values of young and old age groups were statistically same. PBF was significantly high in elder subjects. There was no statistical difference in mean PBFb and PBFf in young subjects but the difference was significant in elder subjects. The PBFf values were highly correlated (r: 0.92 to 0.96) with PBFb values in young age groups unlike elder groups of both males and females. PBFb based categorization of subjects’ presented totally different scenario compared to results obtained by BMI analysis to assess adiposity. Conclusion: The cases such as increasing fatness with aging even when BMI remains constant, the causes of country or ethnic differences in BMI analysis, poor correlation in PBFb and PBFf values in elder age group emphasize on the limitations of BMI based analysis. PBFb within limitations seems to be an improved phenotypic characteristic over BMI.