Being overweight at midlife may increase risk of death

AORN Journal, Oct, 2006

An increased risk of death may be linked to being overweight during middle age, according to an August 22, 2006, news release from the National Cancer Institute. Previous studies have associated obesity with an increased risk of death, but until this study, an association between being overweight and an increased risk of death was uncertain. Researchers distinguish normal weight, overweight, and obesity by using the body-mass index (BMI) (ie, a person's weight divided by the square of his or her height). A normal BMI is 18.5 to 25, the BMI of people who are overweight is 25 to 29.9, and peapie with a BMI higher than 30 are considered obese.

From 1995 to 2005, researchers examined the health status of 527,265 Americans aged 50 to 71 years. Information was gathered using mailed questionnaires and by surveying death records. Data from participants 50 years of age who had never smoked indicated that the risk of death among participants who were overweight increased by 20% to 40%, and the risk of death among participants who were obese increased two- to three-fold.

Body weight is affected by many factors that complicate the relationship between BMI and mortality, including smoking, chronic illness, age, ethnicity, physical activity, and alcohol consumption. Researchers in this study were able to undertake alternative analyses of subsets of data to account for some of these complexities. For example, the study contained data on more than 186,000 mate and female participants who had never smoked. Additionally, researchers conducted analyses that were restricted to groups without any pre-existing disease, which can lead to weight loss, and disregarded deaths occurring soon after enrollment in the study. Researchers also adjusted for pre-existing disease by having older participants report their weight as it was at 50 years of age, thus recording a weight that was mostly unaffected by the onset of any chronic disease.

New Study Finds That Being Overweight at Middle Age Can Be Harmful (news release, Bethesda, Md: National Cancer Institute, Aug 22, 2006) http://www.cancer.gov/ newscenter/pressreleases/BMImortality (accessed 23 Aug 2006).