Research Review by Dr. Shawn Thistle©

Date:

Apr. 2005

Study Title:

Adiposity as compared with physical activity in predicting mortality among women

Authors:

Hu FB, Willet WC, Li T, Stampfer MJ, Colditz GA, Manson JE

Publication Information:

New England Journal of Medicine 2004; 351(26): 2694-2703.

Summary:

It is no secret that obesity and inactivity are common in modern society. It is known that two thirds of American adults are classified as overweight or obese, and Canadians aren't far behind. The vast majority of these people are also inactive, which only compounds the problem.

It is also known that obesity and inactivity can contribute to many undesirable health consequences, such as heart disease and heart attack, adult onset diabetes, high blood pressure…the list could go on.

This is yet another study utilizing data obtained in the Nurses' Health Study, a long-term cohort study of over 120 000 female nurses that began in 1976, when participants were between the ages of 30-55 and free of major medical problems. Participants were followed for over 20 years and had numerous aspects of their health habits measured and analyzed. This particular study investigated the long-term relationship between body mass index and physical activity, and the influence of both of these factors on overall mortality.

Over 115 000 women were included in this analysis. Detailed discussion of the statistical methods in this study is beyond the purpose of this review - please email me if you have any questions.

Important findings of this part of the Nurses' Health Study include:
  • both excess weight or obesity and inactivity were significantly associated with increased mortality
  • mortality increased monotonically with higher body mass index in women who never smoked
  • in combined analysis, adiposity (being overweight) predicted a higher risk of death regardless of activity level
  • even modest weight gain as an adult (4-10 Kg), regardless of activity level, is associated with a higher risk of death
  • excess weight and inactivity could account for 31% of premature deaths, 59% of cardiovascular disease (!), and 21% of deaths from cancer in non-smoking women
  • the increased risk of death associated with being overweight was NOT negated by increased physical activity
  • the lowest mortality was noted in lean, active, non-smoking women

Conclusions & Practical Application:

This study highlights some important (albeit, seemingly obvious) points. Although this study cohort was comprised of mainly white women, the results have been mirrored in large trials involving men. The take home message here is that being overweight and inactive has dangerous, deleterious health effects (again, seemingly obvious). The numbers continue to paint a grim picture of our society, indicating that as a culture, we are not getting this message.

It seems frustrating that these types of studies keep emerging with little change to human behavior. The bottom line is that we need to lose weight, and increase our level of physical activity. Consult your health care provider to have your specific needs assessed. A properly designed exercise program can help prevent many chronic diseases and contribute to a healthy lifestyle.