title: Risk factors for overweight among Brazilian adolescents of low-income families: a case-control study.
abstract: OBJECTIVE
  To study risk factors for overweight among Brazilian adolescents of low-income families.
  
  
  METHODS
  Case-control study of obese and non-obese adolescents.
  
  
  METHODS
  Anthropometric survey including 1420 students (aged 14-19 years) attending a public high school in São Paulo, Brazil.
  
  
  METHODS
  Selection of 83 overweight (body mass index (BMI) >85th percentile) and 89 non-overweight (BMI >5th percentile and <85th percentile) subjects, frequency-matched by age, gender, pubertal development and socio-economic status. Among the nutritional, familial and behavioural data available, five covariates (parents' obesity, adolescents' past obesity, to have a best friend, dietary restriction and habit of napping) were included in the fitted hierarchical conditional logistic regression models.
  
  
  METHODS
  Parents or guardians and adolescents were weighed, measured and answered a pre-tested questionnaire applied by trained nutritionists and paediatricians.
  
  
  RESULTS
  The prevalence of overweight was 15.2%. As previous risks, obese parents and obesity during infancy presented odds ratios (OR) and 95% confidence intervals (CI) of 2.23 (1.15-4.35) and 3.60 (1.47-8.80), respectively. As concurrent factors, the habit of napping, to have a best friend and reported dietary restriction presented OR (95% CI) of 3.43 (1.32-8.92), 5.15 (1.76-15.07) and 7.26 (2.95-17.88), respectively. Dietary patterns, frequency of obesogenic foods and other physical activity indicators presented no statistical significance.
  
  
  CONCLUSIONS
  In case-control studies, OR may overestimate the true risks. Parents' obesity and previous childhood obesity were identified as risk factors; therefore these factors should be the target for preventive programmes and policies in order to prevent the burden of obesity in the near future.
authors.affiliation: Discipline of Nutrition & Metabolism, Department of Pediatrics, Federal University of São Paulo, Rua Loefgreen 1647, 04040-032 São Paulo, SP, Brazil. taddei.dped@epm.br
authors.forename: Daniela
authors.initials: D
authors.lastname: Silveira
authors.forename: José Augusto de Aguiar Carrazedo
authors.initials: JA
authors.lastname: Taddei
authors.forename: Maria Arlete Meil Schimith
authors.initials: MA
authors.lastname: Escrivão
authors.forename: Fernanda Luisa Ceragioli
authors.initials: FL
authors.lastname: Oliveira
authors.forename: Fabio
authors.initials: F
authors.lastname: Ancona-Lopez
mesh_terms: D000293:Adolescent; D017195:Adolescent Nutritional Physiological Phenomena; D000328:Adult; D000886:Anthropometry; D015992:Body Mass Index; D001938:Brazil / Q000453:epidemiology; D016022:Case-Control Studies; D016001:Confidence Intervals; D004038:Diet, Reducing; D005192:Family Health; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D009765:Obesity / Q000453:epidemiology* / Q000209:etiology; D016017:Odds Ratio; D050177:Overweight; D010290:Parents / Q000523:psychology; D011203:Poverty; D012307:Risk Factors; D012959:Socioeconomic Factors; D013334:Students