Prior studies had focused on short-term weight loss. Data were lacking about the optimal degree and amount of physical activity for long-term weight loss.
The study--"Effect of Exercise Dose and Intensity on Weight Loss in Overweight, Sedentary Women: A Randomized Trial"--appears in the September 10, 2003, issue of The Journal of the American Medical Association (JAMA).
The same issue of JAMA also includes an article on recreational physical activity and breast cancer risk. The study, based on data from the Women's Health Initiative's Observational Study, found that increased physical activity was associated with a reduced risk for breast cancer in postmenopausal women. Longer duration physical activity gave the most benefit but the physical activity did not need to be strenuous to reduce breast cancer risk.
The exercise dose and intensity trial involved 201 overweight but otherwise healthy women ages 21-45. All received reduced calorie meals in addition to being randomly assigned to one of four physical activity regimens, which varied by intensity and duration. The regimens consisted of either a moderate- or vigorous-intensity physical activity performed for either a shorter (2 ½ to 3 ½ hours per week) or longer (3 ½ to 5 hours per week) duration. The physical activity consisted primarily of brisk walking, and the regimens used about 1,000 or 2,000 kcal per week.
Women in all four groups lost a significant amount of weight--about 13 to 20 pounds--and maintained their weight loss for a year. They also improved their cardiorespiratory fitness. However, the amount of weight lost or fitness improvement was not different among the four groups.
To arrange an interview about the physical activity and weight loss study, contact the NHLBI Communications Office at 301-496-4236.
To arrange an interview about the physical activity and breast cancer study, contact the National Cancer Institute Press Office at 301-496-6641.
NHLBI press releases, fact sheets, and other materials are available online at http://www.