While past studies have shown that persons in their seventies who carried a few extra pounds live longer than their thinner counterparts, a new study reveals the opposite finding.
Research recently published in the Journal of the American Geriatrics Society showed that men over 75 with a body mass index (BMI) greater than 22.3 had a 3.7-year shorter life expectancy, and women over 75 with a BMI greater than 27.4 had a 2.1-year shorter life expectancy. Generally, a BMI between 18.5 and 24.9 is considered normal weight and a BMI of 25 to 29.9 is considered overweight. A BMI of 30 or more is considered obese.
Earlier studies found a protective association for a high body weight among the elderly. Pramil N. Singh, DrPH, lead author of the paper, said the data from many past studies is problematic because only a single baseline measure of weight was taken, which does not account for weight changes or how weight changes affect life expectancy. Also, most past studies had mortality surveillance of fewer than 19 years, which analyses have shown to be an inadequate amount of time to study risks associated with weight.
The study looked at 6,030 adults who never smoked and who were free of major chronic diseases at enrollment. It then examined only those adults who maintained a stable weight. This was done in an effort to exclude individuals who, for example, were in the normal weight category because they experienced significant weight loss due to a disease. Therefore their death would not have been related to their normal weight, but rather to the disease that caused them to reach normal weight.
“When you control for confounding by disease-related weight loss, overweight and obesity remain a risk for persons over the age of 75,” said Dr. Singh. “This suggests that elderly individuals of normal weight should continue to maintain their weight.”