Correlation of Body Mass Index with Percent Body Fat (PBF) and Comparative Analysis of PBF by Siri's and Goel's Equations for Asian Indians

The aim of this study was to find out the correlation of BMI with per cent body fat and applicability of BMI in predicting malnutrition in field studies and compare the per cent body fat obtained from the conventional Siri's predictive equation for general population and with Goel's equation for Asian Indians on a group of Indian adults. A total of 420 adults, belonging to different Body Mass Index category as per WHO selected from Kochi in Kerala State of India formed the study sample. Body fat per cent calculated from body density using Siri's equation were 14.9, 24.0±5.2 and 30.5±6.7 respectively for underweight, normal and overweight males whereas for female the respective values were 22.3±2.8, 32.3±5.6 and 39.2±6.6. The per cent body fat obtained by Goel's equation was 12.9±3.5, 21.8±3.2 and 35.7±9.9 for underweight, normal and overweight respectively. For their female counterparts the respective values were 20.1±3.3, 32.3±4.0 and 45.2±7.6. Statistical analysis showed significant association between BMI and PBF obtained from Siri's predictive equation and Goel's equation. Goel's equation was found to be highly correlated to BMI (r = 0. 854, p<0.01). This study indicated the applicability of BMI in determining the percentage undernutrition and overnutrition at the field level and the new prediction equation for Asian Indians by Goel is more valid for the selected population when compared with the Siri's equation.