title: Age at dieting onset, body mass index, and dieting practices. A twin study.
abstract: OBJECTIVE
  Using a twin study design, we sought to determine whether an early age at dieting onset is a risk factor for higher adult body mass index (BMI) or use of risky dieting practices, independent of genetic and familial factors.
  
  
  METHODS
  Female twins ages 18-60 years (N=950) from the University of Washington Twin Registry completed 2 surveys an average of 3 years apart. Analyses of individual twins and within-twin pairs tested associations of self-reported age at dieting onset with (1) adult BMI at baseline, (2) change in BMI between the two surveys and (3) risky dieting behaviors at baseline.
  
  
  RESULTS
  In analyses mimicking studies of unrelated individuals, an earlier age at dieting onset was associated with greater adult BMI (p=0.003), higher Restraint Scale scores (p<0.001), greater use of risky dieting behaviors (p=0.04) and more weight cycling episodes (p<0.001). In within-pair models that control for genetic and familial factors, the only significant association was between an earlier age at dieting onset and more weight cycling episodes (p=0.006).
  
  
  CONCLUSIONS
  Underlying genetic and familial factors may influence associations of early dieting with higher adult BMIs and risky dieting practices in women.
authors.affiliation: Program in Nutritional Sciences, University of Washington, United States.
authors.forename: Erin
authors.initials: E
authors.lastname: Enriquez
authors.forename: Glen E
authors.initials: GE
authors.lastname: Duncan
authors.forename: Ellen A
authors.initials: EA
authors.lastname: Schur
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D004038:Diet, Reducing; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008875:Middle Aged; D012189:Retrospective Studies; D011795:Surveys and Questionnaires; D013997:Time Factors; D015431:Weight Loss / Q000502:physiology*; D055815:Young Adult
keywords: Age of dieting onset; Body mass index; Dieting; Twin studies
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