WARNING: the interactive features of this website use CSS3, which your browser does not support. To use the full features of this website, please update your browser.
Abstract
Given clear evidence that smoking lowers weight, it is possible that individuals with higher body mass index (BMI) smoke in order to lose or maintain their weight. We used genetic variants associated with body mass index in a Mendelian Randomisation analysis to investigate whether BMI causes differences in smoking behaviour. We looked at both self-reported smoking behaviour in UK Biobank at more objective measures of smoking behaviour, DNA methylation and cotinine in the Avon Longitudinal Study of Parents and Children and at nicotine metabolism. Our results indicate that higher BMI increases lifetime smoking, smoking heaviness, increases risk of starting smoking and affects smoking related DNA methylation. We found no clear evidence for an effect of BMI on cotinine. It is likely that there is a causal effect of BMI on smoking, but the relationship is likely to be complex due to opposing effects on behaviour and metabolism.