The influence of smoking cessation on body weight may be temporary.

Abstract
The relationships of bodyweight and body mass index with smoking cessation were examined among 1633 adults in Humboldt, Saskatchewan, Canada. Mean body mass index was highest in ex-smokers and lowest in smokers, and that of non-smokers was intermediate. Body mass index decreased significantly with increasing years after smoking cessation in female ex-smokers after adjusting for age, education, location of work, and physical activity. This trend, however, was not significant in men. The body weight data showed similar results. The prevalence of obesity (body mass index greater than 30 kg/m2) in all subjects showed a decrease with increasing years after smoking cessation.