Ten-year weight gain in smokers who quit, smokers who continued smoking and never smokers in the United States, NHANES 2003-2012.

BACKGROUND/
OBJECTIVES: Weight gain after quitting smoking is a common concern for smokers and can discourage quit attempts. The purpose of this analysis was to describe the long-term weight gain, smoking cessation attributable (SCA) weight gain and describe their relationship to cigarette consumption and body mass index (BMI) 10 years ago in a contemporary, nationally representative sample of smokers who continued to smoke and those who quit. SUBJECTS/
METHODS: In all, 12,204 adults ⩾36 years old were selected from the 2003-2012 National Health and Nutrition Examination Survey (NHANES). Ten-year weight gain for never, continuing and former smokers (who quit 1-10 years ago) was calculated by body mass index (BMI) 10 years ago and cigarettes per day (CPD). SCA weight gain was calculated by taking the difference between the adjusted mean 10-year weight gain of former smokers and that of continuing smokers.
RESULTS: Mean 10-year weight gain among continuing smokers was 3.5  versus 8.4 kg among former smokers; the SCA weight gain was 4.9 kg. After Bonferroni correction, there was no significant difference in overall weight gain between continuing and former smokers of 1-14 CPD, and SCA weight gain was lowest in this group (2.0 kg, confidence interval (CI): 0.3, 3.7). SCA weight gain was highest for former smokers of ⩾25 CPD (10.3 kg, CI: 7.4, 13.2) and for those who were obese (7.1 kg, CI: 2.9, 11.3) mostly because of lower than average weight gain or weight loss among continuing smokers in these groups.
CONCLUSIONS: In a current, nationally representative sample, baseline BMI and CPD were important factors that contributed to the magnitude of long-term weight gain following smoking cessation. Light to moderate smokers (<15 CPD) experienced little SCA weight gain, whereas heavy smokers (⩾25 CPD) and those who were obese before quitting experienced the most.