Overweight elderly don't have higher death rates

Reuters, Thu Jun 28, 2:44 PM ET

After the age of 80, carrying a few extra pounds may not subtract years from your lifespan, a new study from Japan shows.

Among a group of 80-year-olds followed for four years, the researchers found that underweight individuals were more likely to die from cancer, heart disease or pneumonia than normal-weight or overweight people. "Overweight status was associated with longevity and underweight with short life," Dr. Yutaka Takata and colleagues from Kyushu Dental College in Kitakyushu City conclude.

While being overweight has been tied to a greater risk of heart disease, studies have also found that being underweight with heart disease may carry an increased risk of morbidity and mortality, Takata and his team note.

To better understand the controversial relationship between body mass index (BMI) and mortality from heart disease, as well as all-cause mortality, the researchers looked at men and women who were 80-years-old.

Fifty-two were underweight, with an average BMI of 17.2; another 468 were normal-weight, with BMIs averaging 21.8; and 155 were overweight, with an average BMI of 27.3. Just five people in the study were obese (with a BMI of 30 or greater), so they were included in the overweight group. People with BMIs between 18.5 and 25 are considered normal weight, while individuals with BMIs of 25 or greater are classified as overweight.

Mortality rates from heart disease, pneumonia and cancer for normal-weight and overweight individuals weren't significantly different, the researchers found. But underweight men and women were nearly four times as likely to die from any cause compared with as overweight individuals, and nearly 18 times more likely to die from cancer. Heart disease mortality in the underweight group was almost four times greater than among normal-weight individuals.

Other studies have found a protective effect of extra pounds among older individuals, Takata and his colleagues note; for example, among elderly US men, the lowest mortality is seen among men with BMIs of 26 and among women with BMIs of 29.6. While Takata and his colleagues attempted to control for the effects of illness, it is still possible that existing disease accounted for some of the increased mortality risk seen among the underweight individuals, they note.

"It is likely that only mild obesity (but not severe obesity) or overweight status in older people and in patients with heart disease may be associated with a lower mortality rate from any disease, as well as with lower mortality from cardiovascular disease," the researchers conclude.

SOURCE: Journal of the American Geriatrics Society, June 2007.