A new research indicates that people who are genetically prone to being overweight have a higher risk of taking up smoking, WHO scientists said.
According to Dr Paul Brennan, a genetic epidemiology expert with the International Agency for Research on Cancer (IARC), obese people are also likely to smoke more than average.
IARC is a WHO agency mandated to conduct research on the causes of cancer and its prevention.
Brennan said around 70 genes have been identified for the first time that could explain this behaviour.
The study is published on Thursday in theÂ British Medical JournalÂ and funded by Cancer Research UK.
It found that increased body mass index (BMI), body fat percentage and even waist circumference were associated with â€œa higher risk of being a smoker, and with greater smoking intensity, measured by the number of cigarettes smoked per dayâ€.
â€œBased on genetic markers of obesity, the study allows us to better understand the complex relationship between obesity and important smoking habits,â€ said Brennan, one of the authors of the study.
He added that the study showing the relationship between body mass and smoking also suggested that there was possibly a â€œcommon biological basis for addictive behaviours, such as nicotine addiction and higher energy intakeâ€.
Brennan also noted that in understanding the link better, it could also be useful as a tool in helping people to stop smoking â€“ a habit that kills more than seven million people each year, according to WHO.
â€œIt is well established that smokers have a lower body weight on average than non-smokers, possibly due to reduced appetite, but that many gain weight after they stop smoking.
â€œHowever, among smokers, those who smoke more intensively, tend to weigh more,â€ IARC said.
IARC Director, Dr Christopher Wild, said that â€œprevention of smoking is key to reducing the global burden of cancer and other chronic diseases, such as cardiovascular disease and diabetesâ€.
Wild added that obesity was among the most important preventable causes of those chronic illnesses.
â€œThese new results provide intriguing insights into the potential benefits of jointly addressing these risk factors,â€ he said. (NAN)