Excessive adiposity at low BMI levels among women in rural Bangladesh

Asian populations have a higher percentage body fat (% BF) and are at higher risk for CVD and related complications at a given BMI compared with those of European descent. We explored whether % BF was disproportionately elevated in rural Bangladeshi women with low BMI. Height, weight, mid-upper arm circumference, triceps and subscapular skinfolds and bioelectrical impedance analysis (BIA) were measured in 1555 women at 3 months postpartum. % BF was assessed by skinfolds and by BIA. BMI was calculated in adults and BMI Z-scores were calculated for females < 20 years old. Receiver operating characteristic (ROC) curves found the BMI and BMI Z-score cut-offs that optimally classified women as having moderately excessive adipose tissue (defined as > 30 % body fat). Linear regressions estimated the association between BMI and BMI Z-score (among adolescents) and % BF. Mean BMI was 19.2 (SD 2.2) kg/m(2), and mean % BF was calculated as 23.7 (SD 4.8) % by skinfolds and 23.3 (SD 4.9) % by BIA. ROC analyses indicated that a BMI value of approximately 21 kg/m(2) optimised sensitivity (83.6 %) and specificity (84.2 %) for classifying subjects with > 30 % body fat according to BIA among adults. This BMI level is substantially lower than the WHO recommended standard cut-off point of BMI >= 25 kg/m(2). The equivalent cut-off among adolescents was a BMI Z-score of -0.36, with a sensitivity of 81.3 % and specificity of 80.9 %. These findings suggest that Bangladeshi women exhibit excess adipose tissue at substantially lower BMI compared with non-South Asian populations. This is important for the identification and prevention of obesity-related metabolic diseases.