title: Occupational class differences in body mass index and weight gain in Japan and Finland.
abstract: BACKGROUND
  Occupational class differences in body mass index (BMI) have been systematically reported in developed countries, but the studies have mainly focused on white populations consuming a Westernized diet. We compared occupational class differences in BMI and BMI change in Japan and Finland.
  
  
  METHODS
  The baseline surveys were conducted during 1998-1999 among Japanese (n = 4080) and during 2000-2002 among Finnish (n = 8685) public-sector employees. Follow-up surveys were conducted among those still employed, in 2003 (n = 3213) and 2007 (n = 7086), respectively. Occupational class and various explanatory factors were surveyed in the baseline questionnaires. Linear regression models were used for data analysis.
  
  
  RESULTS
  BMI was higher at baseline and BMI gain was more rapid in Finland than in Japan. In Finland, baseline BMI was lowest among men and women in the highest occupational class and progressively increased to the lowest occupational class; no gradient was found in Japan (country interaction effect, P = 0.020 for men and P < 0.0001 for women). Adjustment for confounding factors reflecting work conditions and health behavior increased the occupational class gradient among Finnish men and women, whereas factors related to social life had no effect. No statistically significant difference in BMI gain was found between occupational classes.
  
  
  CONCLUSIONS
  The occupational class gradient in BMI was strong among Finnish employees but absent among Japanese employees. This suggests that occupational class inequalities in obesity are not inevitable, even in high-income societies.
authors.affiliation: Population Research Unit, Department of Social Research, University of Helsinki.
authors.forename: Karri
authors.initials: K
authors.lastname: Silventoinen
authors.forename: Takashi
authors.initials: T
authors.lastname: Tatsuse
authors.forename: Pekka
authors.initials: P
authors.lastname: Martikainen
authors.forename: Ossi
authors.initials: O
authors.lastname: Rahkonen
authors.forename: Eero
authors.initials: E
authors.lastname: Lahelma
authors.forename: Michikazu
authors.initials: M
authors.lastname: Sekine
authors.forename: Tea
authors.initials: T
authors.lastname: Lallukka
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005260:Female; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D054624:Health Status Disparities; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology*; D009790:Occupations / Q000145:classification*; D017150:Public Sector; D012307:Risk Factors; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D015430:Weight Gain; D055815:Young Adult