Women and Body Mass Index

New Study Shows That Cardiorespiratory Fitness is
Stronger Predictor of All-Cause Mortality Than BMI in Women

DALLAS — A new study from The Cooper Institute shows that using body mass index (BMI) to predict the risk of all-cause mortality in women may be misleading unless cardiorespiratory fitness levels (CRF) are taken into account. Published in the June 2002 issue of Obesity Research, this is the first study of its kind to examine the effects of BMI and CRF on all-cause mortality in women.

Lead researcher Stephen Farrell, Ph.D., co-authors LeeAnn Braun, M.S., Yiling Cheng, M.D., Ph.D., Carolyn Barlow, M.S., and Steven Blair, P.E.D., followed a group of 9,925 women with an average age of 43 years who were assessed at Cooper Clinic between 1970 and 1996. CRF was measured via a maximal treadmill exercise test and participants were divided into three categories: low fitness, moderate fitness and high fitness. Participants were divided into three BMI categories: normal weight, overweight and obese. BMI is calculated using the following formula: [body weight in pounds multiplied by 703] divided by height in inches.

The group was followed for an average of 11.4 years. During that time, 195 deaths occurred with cancer and cardiovascular disease accounting for 83 percent of the deaths. It was found that having a moderate to high level of CRF resulted in a 43 to 52 percent reduced risk of death in all women regardless of BMI. After controlling for CRF level, being overweight or obese did not significantly contribute to an increased risk of all-cause mortality in these analyses.

The results of this study show that CRF is a stronger predictor of all-cause mortality in women than BMI. "This study should lead physicians and other health care professionals to spend at least as much time counseling their unfit female patients to become more physically fit as they do counseling overweight and obese women to lose weight," stated Farrell.

ABOUT THE COOPER INSTITUTE
The Cooper Institute is a nonprofit research and education center founded in 1970 by preventive medicine pioneer Kenneth H. Cooper, M.D., M.P.H. The Institute is recognized for its programs that focus on exercise physiology, behavior change, children's health, obesity, nutrition, aging, diabetes, hypertension, physical activity intervention and health promotion. Their offices are located in Dallas and Denver. For more information about The Cooper Institute, visit www.cooperinst.org.

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