Cross-sectional study on the relationship between body mass index and smoking, and longitudinal changes in body mass index in relation to change in smoking status: the Tromso Study

Scand J Public Health. 2008 Jun;36(4):397-407. doi: 10.1177/1403494807088453.


Aims: To evaluate the effects of smoking and other lifestyle factors on body mass index (BMI), and changes in BMI in relation to changes in smoking status.

Methods: A cross-sectional study was performed on 10,920 males (3937 smokers) and 12,090 females (4343 smokers) who participated in the fourth Tromsø Study (performed in 1994-95). A longitudinal study was performed on 2364 males (732 smokers in 1994-95) and 2738 females (942 smokers in 1994-95) who participated in both the fourth and the fifth Tromsø studies (performed in 2001).

Results: In the cross-sectional study, current smokers of both genders had a lower BMI (25.0+/-3.4 vs. 25.5+/-3.2 kg/m(2) in males, and 23.9+/-3.9 vs. 25.3+/-4.6 kg/m( 2) in females, p<0.01), a lower degree of physical activity, and a higher consumption of coffee and alcohol than never-smokers. We found a U-shaped relationship between number of cigarettes smoked per day and BMI, with the lowest BMI in those smoking 6- 10 cigarettes per day. Heavy smokers and never-smokers had similar BMI. In the longitudinal study, continuing smokers had a smaller increase in BMI than those who gave up smoking. In those who gave up smoking, there was a significant, positive relationship between number of cigarettes smoked in 1994-95 and increase in BMI.

Conclusions: There is a U-shaped relationship between number of cigarettes smoked per day and BMI. Smoking cessation is associated with an increase in weight as compared to those who continue smoking.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Body Mass Index*
  • Cross-Sectional Studies
  • Female
  • Humans
  • Life Style*
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Norway / epidemiology
  • Obesity / epidemiology
  • Smoking / adverse effects*
  • Smoking Cessation
  • Surveys and Questionnaires
  • Weight Gain