Weight gain has long been associated with quitting smoking, but new European research has found that giving up cigarettes can lead to more weight gain than originally thought.
A study conducted in the UK and France has found that giving up smoking will usually lead to a weight gain of between 4kg and 5kg, more than the average 2.9kg expected by quitters.
But researchers at France's National Institute of Health and Medical Research (INSERM) and the UK's University of Birmingham stressed they didn't want their findings, in any way, to discourage people from quitting smoking.
They said that although more weight is gained by those who quit, the health benefits of quitting smoking far outweigh the harm of putting on some extra kilos.
"Although obesity is positively associated with an increased risk of all causes mortality, cohort studies indicate that modest weight gain does not increase the risk of death; smoking does," the researchers wrote in the British Medical Journal.
The aim of the research was to find out the impact that quitting smoking would have on body weight in those who quit successfully.
Those who quit smoking without the help of nicotine replacement therapy gained an average of 1.1kg in the first month, 2.3kg by the second month, 2.9kg by the third month, 4.2kg by the sixth month and 4.7kg after a year.
The study found that 34 per cent gained 5kg to 10kg, while up to 13 per cent gained more than 10kg.
But it's not all bad news, with 16 per cent losing weight. The researchers noted a large variation in weight change depending on the individual.
"That's more than people have previously said and also it varies a lot between people," said Professor Paul Aveyard, who helped conduct the study.
"Some people don't put on any weight at all, while others put on maybe 10kg in the first year."
Some anti-smoking activists are concerned that the research will deter people from quitting, especially women.
Researchers involved in the European study have suggested, that while more research needs to be done on which people have a greatest risk of losing weight, the current results can be used by doctors to provide those who have decided to quit with a realistic range of weight gains and goals.