title: The effect of school on overweight in childhood: gain in body mass index during the school year and during summer vacation.
abstract: OBJECTIVE
  To determine whether school or nonschool environments contribute more to childhood overweight, we compared children's gains in body mass index (BMI) when school is in session (during the kindergarten and first-grade school years) with their gains in BMI when school is out (during summer vacation).
  
  
  METHODS
  The BMIs of 5380 children in 310 schools were measured as part of the Early Childhood Longitudinal Study, Kindergarten Cohort. We used these measurements to estimate BMI gain rates during kindergarten, summer, and first grade.
  
  
  RESULTS
  Growth in BMI was typically faster and more variable during summer vacation than during the kindergarten and first-grade school years. The difference between school and summer gain rates was especially large for 3 at-risk subgroups: Black children, Hispanic children, and children who were already overweight at the beginning of kindergarten.
  
  
  CONCLUSIONS
  Although a school's diet and exercise policies may be less than ideal, it appears that early school environments contribute less to overweight than do nonschool environments.
authors.affiliation: Department of Sociology and the Initiative for Population Research, Ohio State University, Columbus, OH 43210, USA. von-hippel.1@sociology.osu.edu
authors.forename: Paul T
authors.initials: PT
authors.lastname: von Hippel
authors.forename: Brian
authors.initials: B
authors.lastname: Powell
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Downey
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Rowland
mesh_terms: D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004032:Diet; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D050177:Overweight; D012307:Risk Factors; D012574:Schools; D012621:Seasons; D015430:Weight Gain