title: Weight gain in older adolescent females: the internet, sleep, coffee, and alcohol.
abstract: OBJECTIVE
  To examine whether excessive recreational Internet time, insufficient sleep, regular coffee consumption, or alcoholic beverages promote weight gain.
  
  
  METHODS
  A longitudinal cohort of >5000 girls (Growing Up Today Study), from all over the United States and aged 14 to 21 years, returned surveys in 2001 reporting typical past-year recreational Internet time, sleep, coffee (with caffeine), and alcohol consumption. We estimated correlations among these 4 exposures. Each girl also reported her height and weight in 2000 and again in 2001. Multivariate models investigated associations between 1-year change in body mass index and same-year exposures, adjusted for adolescent growth/development, activity, and inactivity.
  
  
  RESULTS
  The exposures were highly (P < .0001) correlated with each other, except for coffee with Internet time (P > .50). More Internet time, more alcohol, and less sleep were all associated (P < .05) with same-year increases in body mass index. Females, aged 18+ years, who slept <or=5 hours/night (P < .01) or who consumed alcohol 2+servings/week (P < .07) gained more body mass index from 2000 to 2001. For females in weight-promoting categories of all exposures, this translates to nearly 4 extra pounds gained over 1 year. We found no evidence that drinking coffee promotes weight gain.
  
  
  CONCLUSIONS
  Older girls may benefit from replacing recreational Internet time with sleep and by avoiding alcohol.
authors.affiliation: Department of Medicine, Channing Laboratory, Brigham & Women's Hospital and Harvard Medical School Boston, MA 02115, USA. Catherine.Berkey@channing.harvard.edu
authors.forename: Catherine S
authors.initials: CS
authors.lastname: Berkey
authors.forename: Helaine R H
authors.initials: HR
authors.lastname: Rockett
authors.forename: Graham A
authors.initials: GA
authors.lastname: Colditz
mesh_terms: D000293:Adolescent; D000328:Adult; D000428:Alcohol Drinking; D001835:Body Weight; D002110:Caffeine / Q000009:adverse effects*; D003069:Coffee / Q000009:adverse effects*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D020407:Internet; D008019:Life Style; D008137:Longitudinal Studies; D011998:Recreation; D012890:Sleep; D015430:Weight Gain
chemical_list: D003069:Coffee; D002110:Caffeine