title: Combined influence of lifestyle risk factors on body fat in Spanish adolescents--the Avena study.
abstract: OBJECTIVE
  To examine the combined influence of four lifestyle risk factors related to physical activity, television viewing, sleep duration, and meal frequency on body fat (BF) in adolescents.
  
  
  METHODS
  This cross-sectional study comprised 1,310 Spanish adolescents (age 13-18.5 years). Lifestyle variables were self-reported and BF indicators (weight, height, six skinfold thicknesses, waist circumference) measured during the years 2000-2002. Lifestyle risk factors were: physically inactive, ≥ 3 h/day watching television, <8 h/day sleep duration, and <5 meals a day. The number of lifestyle risk factors was calculated for each participant, ranging from 0 to 4.
  
  
  RESULTS
  The number of lifestyle risk factors was positively associated with sum of six skinfolds, %BF, waist circumference, and waist-height ratio (all p < 0.001). The odds ratios (95% confidence interval) of overweight (including obesity) for groups with 1, 2, and 3-4 lifestyle risk factors compared with those with 0 were 2.86 (1.77-4.62), 3.61 (2.16-6.04), and 5.81 (3.07-10.99), respectively (p for trend <0.001). All the observations were independent of age, gender, race, socioeconomic status, and fat free mass.
  
  
  CONCLUSIONS
  The combined influence of four lifestyle risk factors is positively associated with BF and an approximately sixfold risk of overweight in adolescents.
authors.affiliation: Immunonutrition Research Group, Department of Metabolism and Nutrition, Institute of Food Science and Technology and Nutrition (ICTAN), Spanish National Research Council (CSIC), Madrid, Spain. d.martinez@uam.es
authors.forename: David
authors.initials: D
authors.lastname: Martinez-Gomez
authors.forename: Luis A
authors.initials: LA
authors.lastname: Moreno
authors.forename: Javier
authors.initials: J
authors.lastname: Romeo
authors.forename: Pablo
authors.initials: P
authors.lastname: Rey-López
authors.forename: Ruth
authors.initials: R
authors.lastname: Castillo
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Cabero
authors.forename: Germán
authors.initials: G
authors.lastname: Vicente-Rodriguez
authors.forename: Angel
authors.initials: A
authors.lastname: Gutiérrez
authors.forename: Oscar L
authors.initials: OL
authors.lastname: Veiga
mesh_terms: D000273:Adipose Tissue; D000293:Adolescent; D000294:Adolescent Behavior; D001823:Body Composition; D001827:Body Height; D003430:Cross-Sectional Studies; D005247:Feeding Behavior; D005260:Female; D015438:Health Behavior; D006801:Humans; D008019:Life Style; D008297:Male; D009765:Obesity / Q000209:etiology*; D016017:Odds Ratio; D012307:Risk Factors; D057185:Sedentary Behavior; D057566:Self Report; D012885:Skinfold Thickness; D012890:Sleep; D013030:Spain; D013690:Television; D055105:Waist Circumference