Women have today been told by medical experts that increased bicycle riding and brisk walking is the secret to less weight gain.

Research published today in the Archives of Internal Medicine found that for pre-menopausal women, cycling or a brisk walk was associated with putting on less weight; particularly for those who are already overweight or obese.

The US study identified that some 66 per cent of adults are overweight or obese in the country, while 16 per cent of children and adolescents are overweight and another 34 per cent of children and adolescents are at risk of being overweight.

The study suggested that this may be down to the fact that only around 0.5 per cent of the commuting population in the US age 16 and older ride bicycles, of which only 23 per cent are female.

"To our knowledge, research has not been conducted on bicycle riding and weight control in comparison with walking," the authors of the study said.

"Our objective was to assess the association between bicycle riding and weight control in premenopausal women."

Anne Lusk, of the Harvard School of Public Health in Boston, and fellow researchers studied 18,414 women who participated in the Nurses' Health Study II - an ongoing study of more than 116,600 US female nurses aged 25 to 42.

The study - which began in1989 - found that in that year some 50 per cent of the women spent time slow walking, 39 per cent reported spending time walking briskly and 48 per cent reported they spent time riding a bicycle. In 2005, participants on average reported spending more time walking briskly, some time walking slowly and the least amount of time bicycling. Additionally, the average time spent sitting at home was five times as much as time spent in total activity.

According to the results of the study, women who did not bicycle in 1989 but increased their bicycling by 2005 were less likely to have gained weight, even when riding for just five minutes a day.

Even less weight gain was seen with a greater duration of cycling.

The researchers concluded that there was a significant relationship between increased time spent cycling in 2005 and odds of weight gain.

"The benefits of brisk walking, bicycling and other activities were significantly stronger among overweight and obese women compared with lean women, whereas slow walking continued to show no benefit even among overweight and obese women," they said.

"Unlike discretionary gym time, bicycling could replace time spent in a car for necessary travel of some distance to work, shops or school as activities of daily living," the authors conclude.

"Bicycling could then be an unconscious form of exercise because the trip's destination, and not the exercise, could be the goal."