title: Comparison of total energy expenditure between school and summer months.
abstract: BACKGROUND
  Childhood obesity has increased 3 to 4 fold. Some children gain excess weight in summer.
  
  
  CONCLUSIONS
  Total energy expenditure increases almost linearly with fat-free mass. A lower total energy expenditure was not detected in summer.
  
  
  OBJECTIVE
  Recent data report that the youth experience greater weight gain during summer than during school months. We tested the hypothesis that a difference in total energy expenditure (TEE) between school and summer months exists and may contribute to summer weight gain.
  
  
  METHODS
  A secondary analysis was performed on cross-sectional TEE data from school-age, sedentary African-American and Caucasian youth based in or near the District of Columbia who were at-risk for adult obesity because they had body mass index (BMI) ≥ 85th percentile or had overweight parents. TEE was estimated from 18-O and deuterium measurements during 1-week intervals using urine samples collected after ingestion of doubly labelled water. Differences in summer- and school-time TEE were assessed using analysis of covariance. The data were adjusted for fat-free mass (FFM) as determined by deuterium dilution to adjust for the effect of body size on TEE.
  
  
  RESULTS
  Data were collected from 162 youth (average age 10 ± 2 years, BMI 28 ± 8 kg m(-2) and BMI z-score 1.96 + 0.96). Of these, 96 youth had TEE measured during the school year (September-June); 66 different youths had TEE measured during summer months (June-August). After adjustment for FFM, average summertime TEE was 2450 ± 270 kcal d(-1) and average school-time TEE was 2510 ± 350 kcal d(-1) (P = 0.26).
  
  
  CONCLUSIONS
  No difference in TEE was detected between the school year and the summer months. These data suggest that seasonal differences in youth weight gain are not necessarily due to differences in energy expenditures.
authors: Department of Nutritional Sciences, University of Wisconsin - Madison, Madison, WI, USA.
authors: S R J
authors: SR
authors: Zinkel
authors: M
authors: M
authors: Moe
authors: E A
authors: EA
authors: Stern
authors: V S
authors: VS
authors: Hubbard
authors: S Z
authors: SZ
authors: Yanovski
authors: J A
authors: JA
authors: Yanovski
authors: D A
authors: DA
authors: Schoeller
mesh_terms: D001741:Black or African American; D001823:Body Composition; D015992:Body Mass Index; D002648:Child; D003430:Cross-Sectional Studies; D004219:District of Columbia / Q000453:epidemiology; D004734:Energy Metabolism; D005260:Female; D006693:Holidays; D006801:Humans; D008297:Male; D063766:Pediatric Obesity / Q000453:epidemiology / Q000517:prevention & control*; D012574:Schools; D012621:Seasons; D057185:Sedentary Behavior; D015430:Weight Gain; D044465:White People
keywords: Adolescents; doubly labeled water; obesity; overweight; seasonal variation
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