Fear of gaining weight is one of the main reasons that women give for not giving up smoking, but research from US behavioural experts found that exercise helped women stay smoke free.

The study of 281 healthy women gave half of them a standard smoking cessation programme with hard exercises over a 12-week period.

Twice as likely to succeed

It found that the exercising women were twice as likely to stay off the cigarettes.

But the statistics still demonstrate how hard it is to give up smoking.

Only 20% of the exercising women managed to remain cigarette free after the 12 weeks, compared with only one in 10 of the non-exercisers.

One year later, only 11.9% of exercisers, and 5.4% of non-exercisers were non-smokers.

However, nearly half of the women sufficiently motivated to attend most of the workout sessions were still not smoking at the end of the three month trial.

The study did not use nicotine replacement patches.

Bess Marcus, lead author of the "Commit to Quit" programme published in the "Archives of Internal Medicine" said: "The study results clearly indicate that smoking cessation programmes designed for women can be significantly more successful than generic programmes.

"We can build in measures to help women cope with fears of gaining weight if they stop smoking."

Marcus added that men trying to quit smoking would benefit from exercise, and urges doctors to encourage smokers to exercise.