title: Validity of body mass index and waist circumference in the classification of obesity as compared to percent body fat in Chinese middle-aged women.
abstract: OBJECTIVE
  To evaluate the validity of currently recommended obesity cutoffs of body mass index (BMI, in kg/m(2)) and waist circumference (WC, in cm) for Asians by the WHO/IASO/IOTF and for Chinese by the Working Group on Obesity in China (WGOC) using the percentage body fat (%BF)-obesity criteria.
  
  
  METHODS
  A cross-sectional study.
  
  
  METHODS
  A total of 1122 community-based Hong Kong Chinese women aged between 41 and 63 years.
  
  
  METHODS
  Total %BF and percent truncal fat (%TF) were measured using dual-energy X-ray absorptiometry. Anthropometric indices were measured using standard methods.
  
  
  RESULTS
  Regression analyses showed that the BMI cutoffs of 23, 24, 25, and 28 kg/m(2) corresponded to the %BF of 34.8, 35.9, 36.9 and 39.5%, and the 80 cm WC corresponded to 34% TF, respectively. Compared with the %BF obesity cutoff (>/=40%), the WHO/IASO/IOTF BMI-obesity criterion (>/=25) shows a good sensitivity (75%) and specificity (71%); and the WGOC criterion (BMI>/=28) had a low sensitivity (41%) but an excellent specificity (93%), respectively. Corresponding to the BMI cutoffs of 23, 24, 25 and 28 kg/m(2), the %BF cutoffs associated with peak kappa statistic were 33, 34, 35 and 40%, and the relevant %TF linked with 80 cm WC was 33%, respectively.
  
  
  CONCLUSIONS
  BMI and WC have a good accuracy in the prediction of obesity. Our findings suggest that the WGOC BMI cutoffs are appropriate, but 80 cm of WC is a very rigorous cutoff for this population when using the criteria of 34 and 40% of body fat or truncal fat for overweight and obesity.
authors.affiliation: Department of Community & Family Medicine, and the School of Public Health, The Chinese University of Hong Kong, Hong Kong SAR.
authors.forename: Y-M
authors.initials: YM
authors.lastname: Chen
authors.forename: S C
authors.initials: SC
authors.lastname: Ho
authors.forename: S S H
authors.initials: SS
authors.lastname: Lam
authors.forename: S S G
authors.initials: SS
authors.lastname: Chan
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000473:pathology*; D000328:Adult; D000886:Anthropometry / Q000379:methods; D044466:Asian People; D001824:Body Constitution; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008875:Middle Aged; D009765:Obesity / Q000175:diagnosis* / Q000208:ethnology / Q000473:pathology; D015203:Reproducibility of Results