title: Does smoking in adolescence affect body mass index, waist or height? Findings from a longitudinal study.
abstract: OBJECTIVE
  To assess the effect of smoking uptake on body mass index (BMI), waist circumference and height during adolescence.
  
  
  METHODS
  Five-year longitudinal study.
  
  
  METHODS
  Thirty-six schools in South London, England, selected by a stratified random sampling procedure designed to ensure ethnic and socio-economic diversity.
  
  
  METHODS
  A total of 5863 students took part in the HABITS (Health and Behaviour in Teenagers) Study between 1999 and 2003.
  
  
  METHODS
  Self-reported smoking behaviour, saliva cotinine concentrations and measured weight, waist circumference and height were obtained, along with information on gender, ethnicity, socio-economic deprivation, pubertal status, self-reported exercise and dieting. Students were examined annually from school year 7 (ages 11-12) to year 11 (ages 15-16), with response rates ranging from 74 to 84%. A total of 2665 never smokers at year 7 with complete data for years 7 and 11 were included in the analyses.
  
  
  RESULTS
  Adjusting for year 7 BMI and other potential confounders, regular smokers (more than six cigarettes a week) at year 11 had significantly lower BMI (P = 0.002) than other students. Smokers defined by a cotinine above 15 ng/ml also had lower BMI (P < 0.0001). Waist circumferences were lower in regular smokers (P = 0.014) and cotinine-defined smokers (P < 0.011). No consistent association was found between smoking and height. The adjusted difference in weight between regular smokers and other students amounted to 1.8 kg (95% CI, 0.52-3.17) for an average-height student.
  
  
  CONCLUSIONS
  Taking up regular smoking during adolescence may result in a lower BMI, but the effect is small and of uncertain significance.
authors.affiliation: Cancer Research UK Health Behaviour Unit, Department of Epidemiology and Public Health, University College London, London, UK. j.fidler@ucl.ac.uk
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Fidler
authors.forename: Robert
authors.initials: R
authors.lastname: West
authors.forename: Cornelia H M
authors.initials: CH
authors.lastname: Van Jaarsveld
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Jarvis
authors.forename: Jane
authors.initials: J
authors.lastname: Wardle
mesh_terms: D000293:Adolescent; D001827:Body Height; D015992:Body Mass Index; D003376:Counseling / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010379:Peer Group; D012307:Risk Factors; D012649:Self Concept; D012907:Smoking / Q000009:adverse effects* / Q000503:physiopathology; D012959:Socioeconomic Factors; D049629:Waist-Hip Ratio