Body fat percentage and body mass index in a probability sample of an adult urban population in Brazil

The purpose of the present study was to measure body composition in a probability sample of adults (≥ 20 years) living in Niterói, State of Rio de Janeiro, Brazil, and to assess the adequacy of the World Health Organization (WHO) recommended body mass index (BMI) cut-offs values for identifying obesity in this population. Anthropometric measures and percentage body fat (%BF) assessments were taken with 550 fasted individuals (352 women). Obesity was classified according to the WHO recommended BMI cut-off values. %BF predictive equations were developed based on the inverse of BMI. BMI and %BF mean values (standard error) were: 25.3kg/m2 (0.3) and 38% (0.4) for women and 25.1kg/m2 (0.3) and 22.1% (0.6) for men. The predicted %BF values (regression of %BF on the inverse of BMI) for each BMI cut-offs of 18.5, 25 and 30kg/m2 were: 26.3%, 38.6% and 44.5% for women and 5.6%, 23.2% and 31.5% for men, respectively. The BMI values for the %BF-estimated obesity cut-off values were 20.5 for men and 25.7kg/m2 for women. Based on the BMI-%BF relationship, the BMI cut-off values recommended by the WHO are not adequate in identifying obesity in adults from this population.