NHLBI Study Finds Moderate Physical Activity Promotes Weight Loss as well as Intense Exercise

WHI Observational Study Suggests Increased Physical Activity Reduces Breast Cancer Risk

Women trying to lose weight can benefit as much from a
moderate physical activity as from an intense workout,
according to a new study supported by the National Heart,
Lung, and Blood Institute (NHLBI), part of the National
Institutes of Health in Bethesda, MD.

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? to 3? hours per week) or longer (3? 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.