Obesity's effects on mortality may have been over-estimated

New research shows that obese adults who reach the age of 70 are at no greater risk of dying than their non-obese counterparts, but they do have a much greater probability of spending their remaining years disabled. The data supporting this is reported in the August 2005 issue of The Gerontologist (Vol. 45, No. 4).

Previous investigations had focused on the impact of obesity on either mortality or the onset of disability, but lead author Sandra Reynolds of the University of South Florida School of Aging Studies sought to consider them together. She was joined on the study by Yasuhiko Saito of Japan's Nihon University and Eileen M. Crimmins of the Andrus Gerontology Center at the University of Southern California, Los Angeles.

The team defined disability as having difficulty performing one or more activities of daily living (ADLs), such as walking across a room, bathing, eating, dressing, toileting, or transferring in or out of bed. Those who could perform all ADLs were considered active.

Using a sample of over 7,000 seniors, they reported statistical information separately by gender. At 70 years old, the men in the group could expect to live 12.3 years if they were non-obese and 12.4 if they were obese. The non-obese men could expect to live 9.8 active years and 2.5 disabled years. However, the obese men could only expect to live 8.4 active years and 4.0 years with disability.

In the same sample, women aged 70 could expect to live 15.3 years if they were non-obese and 15.5 years if they were obese. These women averaged 10.5 active years and 4.8 disabled years if they were non-obese, but the obese women only lived 8.1 active years and 7.4 disabled years.

This research supports recent assertions by the Centers for Disease Control that prior estimates of obesity's effects on mortality may have been over-estimated, since most studies of obesity do not account for its lesser effects on death rates at old age.