title: Trends in underweight and overweight/obesity prevalence in Chinese youth, 2004-2009.
abstract: BACKGROUND
  There is a paucity of recent data on Chinese childhood overweight and underweight prevalence especially since 2004.
  
  
  OBJECTIVE
  The purpose of this study was to examine trends in underweight and overweight/obesity ("overweight" hereafter) prevalence and energy balance-related behaviors of Chinese youth from 2004 to 2009.
  
  
  METHODS
  Data from the China Health and Nutrition Survey, 2004-2009 (N = 4,061 students aged 6-18 years), were analyzed. Trained health workers took anthropometric measures at the participant's house or at a local clinic following a reference protocol recommended by the World Health Organization. The international age- and sex-specific body mass index reference standard proposed by the International Obesity Task Force was used to define underweight and overweight children in this study.
  
  
  RESULTS
  Among 6- to 11-year-old boys, underweight prevalence increased from 14.5% (2004) to 20.1% (2009, p = 0.068). Among 12- to 18-year-old boys, however, overweight prevalence increased from 7.5 to 12.6% (p = 0.034). From 2004 to 2009, after-school sedentary behavior increased from 2.3 to 3.4 h/day for 6- to 11-year-olds (p < 0.001) and from 2.2 to 3.1 h/day for 12- to 18-year-olds (p < 0.01). Meanwhile, the total energy intake decreased 7% for 6- to 11-year-olds (p < 0.05) and 10% for 12- to 18-year-olds (p < 0.01).
  
  
  CONCLUSIONS
  Both underweight and overweight Chinese students are increasing, with underweight increases more pronounced in 6- to 11-year-olds and overweight increases more pronounced in 12- to 18-year-olds. Nationwide efficacious interventions are needed that improve the diet, decrease sedentary behavior, and encourage a healthy and realistic body image in Chinese youth.
authors.affiliation: College of Health Sciences, Ewha Womans University, 52, Ewhayeodae-gil, Soedaemoon-gu, Seoul, 120-750, South Korea, dseo@ewha.ac.kr.
authors.forename: Dong-Chul
authors.initials: DC
authors.lastname: Seo
authors.forename: Jingjing
authors.initials: J
authors.lastname: Niu
mesh_terms: D000293:Adolescent; D000367:Age Factors; D044466:Asian People; D015992:Body Mass Index; D002648:Child; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000453:epidemiology*; D050177:Overweight / Q000453:epidemiology*; D015995:Prevalence; D012574:Schools; D012737:Sex Factors; D013851:Thinness / Q000453:epidemiology*; D013997:Time Factors