title: Food pattern analysis over time: unhealthful eating trajectories predict obesity.
abstract: BACKGROUND
  Analysis of dietary patterns is prominent in nutrition literatures, yet few studies have taken advantage of multiple repeated measurements to understand the nature of individual-level changes over time in food choice, or the relation between these changes and body mass index (BMI).
  
  
  OBJECTIVE
  To investigate changes in eating patterns at the individual level across three exam periods, and to prospectively examine the relation of eating trajectories to BMI at the cohort level.
  
  
  METHODS
  The study included 3418 participants at baseline. Clinically measured BMI and dietary intake were assessed during three exam periods between 1991 and 2001 using a validated food frequency questionnaire. An individual's eating trajectory across exam periods was analyzed using sequence analysis, and then used to estimate outcomes of continuous BMI and categorical obesity status. Ordinary least squares regression models with robust standard errors were adjusted for socio-economic and demographic confounders, baseline BMI and baseline eating.
  
  
  RESULTS
  A total of 66.2% (n=1614) of participants change their diet pattern during the study period, 33.8% (n=823) remain stable. After accounting for potential confounders, an unhealthful trajectory is significantly associated with a 0.42 kg m(-2) increase in BMI (confidence interval (CI): 0.1, 0.7). Those with an unhealthful trajectory are 1.79 times more likely to be overweight (relative risk ratio, 95% CI: 1.1, 2.8) and 2.4 times more likely to be obese (relative risk ratio, 95% CI: 1.3, 4.4). Moreover, a number of specific diet transitions between exams are predictive of weight gain or loss.
  
  
  CONCLUSIONS
  Contextualizing an individual's current eating behaviors with an eye towards diet history may be an important boon in the reduction of obesity. Although it may not be realistic for many people to shift from the least to most healthful diet, results from this study suggest that consistent movement in an overall healthier direction is associated with less weight gain.
authors.affiliation: School of Public Health, University of California-Berkeley, 50 University Hall, Berkeley, CA 94720-7360, USA. pachucki@berkeley.edu
authors.forename: M A
authors.initials: MA
authors.lastname: Pachucki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D001835:Body Weight; D015331:Cohort Studies; D004032:Diet; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D009765:Obesity / Q000453:epidemiology* / Q000517:prevention & control; D011237:Predictive Value of Tests; D011446:Prospective Studies; D013997:Time Factors; D014481:United States / Q000453:epidemiology