Quitting smoking leads to an average weight gain of four to five kilogrammes (nine to 11 pounds) in the first year -- "significantly" more than previously thought, a study said Wednesday.
Most of the pounds are piled on in the first three months, a team of medical researchers wrote in the online journal bmj.com, as another group stressed that the health benefits of quitting far outweighed the risks of putting on weight.
For quitters who did not use nicotine replacement therapy, the average weight gain was 1.1 kilos at one month, 2.3 kilos at two, 2.9 kilos at three, 4.2 kilos at six months and 4.7 kilos after a year.
This was "substantially higher than the 2.9 kg often quoted in smoking cessation advice leaflets," wrote the team from universities and medical research facilities in France and Britain.
"Moreover, this mean weight gain is greater than the 2.3 kg gain that female smokers report being willing to tolerate, on average, before embarking on a quit attempt."