A new study published this week by the BMJ has revealed that obesity is associated with an increased risk of the frequency and taking up of smoking.
Researchers said that these results suggest that obesity influences smoking behaviour, which could have implications for public health interventions aiming to reduce the prevalence of these important risk factors.
It’s commonly known that, on average, smokers have less body weight than those who don’t smoke but after quitting gain extra weight. However, active smokers who smoke more intensively tend to weigh more than light smokers.
Though this may be due to other lifestyle factors, such as physical inactivity and unhealthy diet, it is also possible that obesity influences smoking uptake and intensity.
Establishing obesity’s link
To better understand these interactions, a team of researchers based in France and the UK set out to determine whether genetic markers associated with obesity play a direct role in smoking behaviour.
The researchers analysed genetic variants with known effects on body mass index (BMI), body fat percentage, and waist circumference for around 450,000 individuals from the UK Biobank database and the Tobacco and Genetics (TAG) consortium.
Three measures of smoking behaviour were assessed:
- Current and past smoking;
- Number of cigarettes smoked per day; and
- Age of smoking initiation.
What the results showed
It was found that each 4.6kg/m2 increase in BMI was associated with an 18% increased risk of being a smoker in UK Biobank data and a 19% increased risk in TAG consortium data. Each increase in BMI was also estimated to increase smoking frequency by around one cigarette per day.
The researchers said: “Our study provides evidence that differences in body mass index and body fat distribution causally influence different aspects of smoking behaviour, including the risk of individuals taking up smoking, smoking intensity, and smoking cessation.
“These results highlight the role of obesity in influencing smoking initiation and cessation, which could have implications for public health interventions aiming to reduce the prevalence of these important risk factors.”
Press release: the BMJ