title: Fast-food habits, weight gain, and insulin resistance (the CARDIA study): 15-year prospective analysis.
abstract: BACKGROUND
  Fast-food consumption has increased greatly in the USA during the past three decades. However, the effect of fast food on risk of obesity and type 2 diabetes has received little attention. We aimed to investigate the association between reported fast-food habits and changes in bodyweight and insulin resistance over a 15-year period in the USA.
  
  
  METHODS
  Participants for the CARDIA study included 3031 young (age 18-30 years in 1985-86) black and white adults who were followed up with repeated dietary assessment. We used multiple linear regression models to investigate the association of frequency of fast-food restaurant visits (fast-food frequency) at baseline and follow-up with 15-year changes in bodyweight and the homoeostasis model (HOMA) for insulin resistance.
  
  
  RESULTS
  Fast-food frequency was lowest for white women (about 1.3 times per week) compared with the other ethnic-sex groups (about twice a week). After adjustment for lifestyle factors, baseline fast-food frequency was directly associated with changes in bodyweight in both black (p=0.0050) and white people (p=0.0013). Change in fast-food frequency over 15 years was directly associated with changes in bodyweight in white individuals (p<0.0001), with a weaker association recorded in black people (p=0.1004). Changes were also directly associated with insulin resistance in both ethnic groups (p=0.0015 in black people, p<0.0001 in white people). By comparison with the average 15-year weight gain in participants with infrequent (less than once a week) fast-food restaurant use at baseline and follow-up (n=203), those with frequent (more than twice a week) visits to fast-food restaurants at baseline and follow-up (n=87) gained an extra 4.5 kg of bodyweight (p=0.0054) and had a two-fold greater increase in insulin resistance (p=0.0083).
  
  
  CONCLUSIONS
  Fast-food consumption has strong positive associations with weight gain and insulin resistance, suggesting that fast food increases the risk of obesity and type 2 diabetes.
authors.affiliation: Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Pereira
authors.forename: Alex I
authors.initials: AI
authors.lastname: Kartashov
authors.forename: Cara B
authors.initials: CB
authors.lastname: Ebbeling
authors.forename: Linda
authors.initials: L
authors.lastname: Van Horn
authors.forename: Martha L
authors.initials: ML
authors.lastname: Slattery
authors.forename: David R
authors.initials: DR
authors.lastname: Jacobs
authors.forename: David S
authors.initials: DS
authors.lastname: Ludwig
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American; D000886:Anthropometry; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology; D004032:Diet; D005247:Feeding Behavior / Q000208:ethnology; D005260:Female; D005502:Food / Q000009:adverse effects*; D006801:Humans; D007333:Insulin Resistance / Q000208:ethnology; D008019:Life Style / Q000208:ethnology; D008297:Male; D009765:Obesity / Q000209:etiology; D012147:Restaurants; D012307:Risk Factors; D015430:Weight Gain / Q000208:ethnology; D044465:White People