Back on track—Smoking cessation and weight changes over 9 years in a community-based cohort study

Abstract Objective To examine the impact of smoking cessation on body weight compared with normal long-term weight development. Methods Of 1970 adults (20–69 years) in a rural town in Denmark invited to take part in the study in 1998–2000, 1374 (70%) participated. After 9 years, 1121 participated in the follow-up study. Weight changes were compared using multivariable regression models. Results The mean baseline weight of never-smokers was 76.4 kg (SD 16.0). The adjusted weight of smokers and ex-smokers differed by − 4.2 kg (95% CI: − 5.9, − 2.6), and − 0.7 kg (95% CI: − 2.5, 1.1), respectively. The adjusted weight gain rate (kg/year) of never-smokers, smokers, and ex-smokers was 0.213, 0.127, and 0.105, respectively. The absolute post cessation weight gain (PCWG) was 5.0 kg (SD 7.0), and the adjusted PCWG was 2.8 kg (95% CI: 1.7, 3.9) compared with never-smokers, and 3.5 kg (95% CI: 2.3, 4.8) compared with smokers. The follow-up weight did not differ between quitters and never-smokers (0.1 kg; 95% CI: − 2.4, 2.6). Conclusion Smokers weigh less than never-smokers. By quitting, they gain weight and end up weighing the same as comparable never-smokers. Weight gain rates differ by smoking status. Consequently, PCWG depends on the length of follow-up. Our graphical model indicates that smoking cessation results in a return to normal weight development.