The association between quitting smoking and weight gain: a systemic review and meta-analysis of prospective cohort studies

• Published in: Obesity reviews Vol. 16; no. 10; pp. 883 - 901
• Main Authors: Tian, J., Venn, A., Otahal, P., Gall, S.
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01-10-2015; Wiley Subscription Services, Inc
• Subjects: Cohort studies; meta-analysis; smoking cessation; weight gain
• ISSN: 1467-7881; 1467-789X
• DOI: 10.1111/obr.12304

Summary
This systematic review and meta‐analysis aimed to quantify weight gain after smoking cessation and the difference in weight gain between quitters and continuing smokers. Five electronic databases were searched before January 2015. Population‐based prospective cohort studies were included if they recorded the weight change of adult smokers from baseline (before smoking cessation) to follow‐up (at least 3 months after cessation). Thirty‐five cohort studies were identified, including 63,403 quitters and 388,432 continuing smokers. The mean weight gain was 4.10 kg (95% confidence interval [CI]: 2.69, 5.51) and body mass index (BMI) gain was 1.14 kg m−2 (95% CI: 0.50, 1.79) among quitters. Compared with continuing smoking, quitting smoking was significantly associated with absolute weight (adjusted mean difference [MD]: 2.61 kg; 95% CI: 1.61, 3.60) and BMI gain (adjusted MD: 0.63 kg m−2; 95% CI: 0.46, 0.80). Subgroup analyses using geographic region found that the difference in weight gain was considerably greater in studies from North America than from Asia. Follow‐up length was identified as a source of heterogeneity, such that studies with longer follow‐up showed greater difference in weight gain. Effective strategies are needed to encourage smokers to quit irrespective of potential weight gain and to help quitters avoid excess weight gain.