title: Association between Smoking Status and Obesity in a Nationwide Survey of Japanese Adults.
abstract: OBJECTIVE
  A positive association between the number of cigarettes smoked per day and obesity has been reported, whereas how other smoking-related indices, such as pack-years and duration of smoking, are related with obesity has been less investigated. We analyzed the age-adjusted cross-sectional association between smoking and obesity in a general Japanese population.
  
  
  METHODS
  We used data from a nationwide epidemiological study of Japanese adults (N = 23,106). We compared the prevalence of obesity (defined as body mass index ≥ 25kg/m2) among groups classified by smoking behavior, pack-years, number of cigarettes per day, duration of smoking, and duration and time of smoking cessation.
  
  
  RESULTS
  In men, current smokers had a lower odds ratio (OR) for obesity of 0.80 (95% confidence interval (CI): 0.72-0.88) compared to non-smokers, whereas past smokers had a higher OR of 1.23 (95% CI: 1.09-1.37) compared to current smokers. In women, there were no differences in obesity between the three groups classified by smoking behavior. However, in both sexes, the prevalence of obesity tended to increase with pack-years and the number of cigarettes per day, but not with duration of smoking in current and past smokers. Further, in male smokers, the risks for obesity were markedly higher in short-term heavy smokers compared with long-term light smokers, even with the same number of pack-years. Regarding the impact of smoking cessation, female past smokers who quit smoking at an age > 55-years had an elevated OR of 1.60 (95% CI:1.05-2.38) for obesity.
  
  
  CONCLUSIONS
  In a general Japanese population, obesity is progressively associated with pack-years and number of cigarettes per day, but not with the duration of smoking. When investigating the association between obesity and cigarette smoking, the daily smoking burden and the duration of smoking require to be independently considered.
authors.affiliation: First Department of Medicine, Hokkaido University School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: First Department of Medicine, Hokkaido University School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: Ichizo
authors.initials: I
authors.lastname: Tsujino
authors.affiliation: First Department of Medicine, Hokkaido University School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Konno
authors.affiliation: Department of Biostatistics, Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan.
authors.forename: Yoichi M
authors.initials: YM
authors.lastname: Ito
authors.affiliation: First Department of Medicine, Hokkaido University School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: Chisa
authors.initials: C
authors.lastname: Takashina
authors.affiliation: First Department of Medicine, Hokkaido University School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Sato
authors.affiliation: First Department of Medicine, Hokkaido University School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Isada
authors.affiliation: First Department of Medicine, Hokkaido University School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ohira
authors.affiliation: First Department of Medicine, Hokkaido University School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Ohtsuka
authors.affiliation: Clinical Research Center for Allergy and Rheumatology, Sagamihara National Hospital, Sagamihara, Kanagawa, Japan.
authors.forename: Yuma
authors.initials: Y
authors.lastname: Fukutomi
authors.affiliation: Department of Environmental and Preventive Medicine, Graduate School of Medical Science, Kanazawa University, Kanazawa, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakamura
authors.affiliation: Department of Internal Medicine, Kurobe City Hospital, Kurobe, Toyama, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kawagishi
authors.affiliation: Department of Medicine, Headquarter of National Hospital Organization, Tokyo, Japan.|Department of Allergy, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.
authors.forename: Chiharu
authors.initials: C
authors.lastname: Okada
authors.affiliation: Department of Pulmonary Medicine, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Hizawa
authors.affiliation: Clinical Research Center for Allergy and Rheumatology, Sagamihara National Hospital, Sagamihara, Kanagawa, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Taniguchi
authors.affiliation: Department of Allergy, Tokyo Metropolitan Children's Medical Center, Tokyo, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Akasawa
authors.affiliation: First Department of Medicine, Hokkaido University School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Nishimura
mesh_terms: D000328:Adult; D000368:Aged; D044466:Asian People; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000209:etiology*; D016017:Odds Ratio; D015995:Prevalence; D012907:Smoking / Q000009:adverse effects*; D016540:Smoking Cessation / Q000379:methods; D011795:Surveys and Questionnaires; D014029:Tobacco Use Disorder / Q000150:complications*; D055815:Young Adult