Obesity is a serious problem worldwide, and especially in the United States, where 66 percent of adults are overweight or obese, and 16 percent of children and adolescents are overweight. Additionally, only about 0.5 percent of those aged 16 and older who commute on a daily basis ride bicycles, of which only 23 percent are women. The authors write, "To our knowledge, research has not been conducted on bicycle riding and weight control in comparison with walking. Our objective was to assess the association between bicycle riding and weight control in pre-menopausal women."
The results of the analysis were published in the Archives of Internal Medicine and were based on 18,414 out of 116,608 women nurses who completed periodic questionnaires as to their diet, weight, health and behaviour over a period of 16 years, from 1989 to 2005. At the beginning of the study the nurses ranged from 25 to 42 years of age. The researchers controlled for other obesity risk factors in order to isolate the effects of exercise.
Though brisk walking and bicycling had an effect on all the women in the study, those who practiced slow walking as their only form of exercise lost no weight at all. The women who reduced the amount of bicycling they did from more than 15 minutes a day to less than 15 minutes over the period of the survey had gained an average of more than four pounds. Women who did not bicycle at all at the beginning of the study, but increased to five minutes of bicycling a day still gained weight, but not as much as the women who never bicycled at all.
The bicycling was found to be most effective in overweight and obese women, who lost the greatest amount of weight by bicycling or walking briskly for 30 minutes per day.
Though the study showed that bicycling was helpful in controlling weight, the positive effects of bicycling only occur with regular practice. The study's main author, Dr. Anne C. Lusk, a research fellow at the Harvard School of Public Health, noted, "This is not suggesting that if you bicycle for five minutes you will immediately go back to the weight you were when you were 18. If that were true, bicycle sales would go through the roof. But it's highly suggestive that bicycling is highly beneficial in women."
The authors conclude, "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. Bicycling could then be an unconscious form of exercise because the trip's destination, and not the exercise, could be the goal."