title: [The association between body mass index, waist circumference with body fat percent, and abdominal fat rate in overweight and obese pupils].
abstract: OBJECTIVE
  To study the association between body mass index(BMI), waist circumference (WC) with body fat percent, and abdominal fat rate in overweight and obese pupils.
  
  
  METHODS
  Using convenience sampling, two primary schools of Dongcheng district in Beijing were selected in May 2010. A total of 162 overweight and obese pupils graded from 2 to 5 who met the criteria of overweight and obese were recruited based on the physical exam record of the school medical department in April. Their physical measurements were taken to measure body fat percent (PBF), abdominal fat rate and visceral fat level and BMI was calculated.Independent-sample t test and Wilcoxon rank sum test were applied to analyze the gender differences. Correlation analysis was used to explore the association between the indexes of fat distribution (PBF, abdominal fat rate and visceral fat level) and BMI and WC.Univariate regression analysis was conducted to determine the variance of three indexes of fat distribution explained by the independent variables.
  
  
  RESULTS
  The PBF of overweight and obese pupils was (43.62 ± 2.98) %, the abdominal fat rate of them was (28.06 ± 6.02)%, the visceral fat level of them was 7.51 ± 3.43, BMI was (23.41 ± 2.83) kg/m(2). WC, PBF and abdominal fat rate were (78.57 ± 7.76) cm, (42.36 ± 2.56) % and (26.47 ± 5.39) % in boys and (73.34 ± 7.22) cm, (45.88 ± 2.26) %, (30.92 ± 6.07) % in girls. The difference in gender was significant (t values were -4.218, 8.751, 4.811, respectively, all P values <0.01). The visceral fat level of boys and girls were 8.86 ± 3.42 and 5.09 ± 1.70, with significant difference (Z = -7.08, P < 0.01). The correlation between PBF and BMI and the variance of PBF explained by BMI (r = 0.563, R(2) = 31.7%) were stronger than them with WC (r = 0.402, R(2) = 16.1%) (P < 0.01). The correlation between visceral fat levels and WC and the variance of visceral fat level explained by WC (r = 0.723, R(2) = 57.3%) were higher than them with BMI (r = 0.621, R(2) = 41.7%) (P < 0.01).
  
  
  CONCLUSIONS
  The correlation and prediction ability of BMI and body fat percent were stronger than WC, while the correlation and prediction ability of WC and visceral fat were higher than BMI.
authors.affiliation: Institute of Child and Adolescent Health, Public Health of Peking University, Beijing 100191, China.
authors.forename: Jing-jing
authors.initials: JJ
authors.lastname: Wang
authors.forename: Hai-jun
authors.initials: HJ
authors.lastname: Wang
authors.forename: Jia-shuai
authors.initials: JS
authors.lastname: Liu
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
mesh_terms: D050153:Abdominal Fat; D000273:Adipose Tissue; D000293:Adolescent; D001823:Body Composition; D015992:Body Mass Index; D002648:Child; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D050177:Overweight / Q000453:epidemiology*; D063766:Pediatric Obesity / Q000453:epidemiology*; D011237:Predictive Value of Tests; D011680:Pupil; D055105:Waist Circumference