Study finds that seniors having extra weight in their 70's have shorter life expectancy compared to those who are thinner.

Researchers from Adventist Health Studies 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 with a BMI greater than 27.4 had a 2.1 year shorter life expectancy. BMI between 18.5 and 24.9 is considered normal and BMI > 25 is considered obese. Body Mass Index (BMI) is the measurement of body fat based on height and weight that applies to adult men and women.

Previous studies found a protective association for a high body weight among elderly, but did not account for weight changes or how weight changes affect life expectancy. Other studies where not long enough to accurately measure the amount of time to study risks associated with weight.

"We had a unique opportunity to do 29 years of follow-up with a cohort that was also followed for mortality outcomes," said Pramil N. Singh, DrPH, lead author of the paper and an associate professor in the School of Public Health at Loma Linda University."Across this long period of time, we had multiple measures of body weight, which provided a more accurate assessment."

The study looked at 6,030 adults who never smoked and who were free of major chronic diseases during the initial enrollment. The researchers than examined only those adults who maintained a stable weight, to exclude those who lost weight due to diseases or other conditions.

"When you control for confounding by disease-related weight loss, overweight and obesity remain a risk for persons over the age of 75," Dr. Singh said. "This suggests that elderly individuals of normal weight should continue to maintain their weight."

Researcher noted that women did not have increased risk of mortality till their body weight exceeds the BMI of 27.4 while men experience a greater risk of mortality at a BMI of 22.3 due to higher sensitivity to body fat in comparison to women.

"This is not to say that extra weight is good for women over 75," Dr. Singh said, "but rather that the negative effects of extra weight in women over 75 appear at a higher weight than in males."

The study is unique do to the religious affiliation of its applicants. All participants were Seventh-day Adventists, who, because of church recommendations, are lifelong non-smokers, consume little if any alcohol, are more physically active, and consume less meat than the general population.

Dr. Singh said further studies are needed to understand the positive and negative effects of lifestyle patterns that help individuals maintain low body weight over long periods of time.