Obesity and a bigger waist size in older women are associated with a higher risk of death, major chronic disease and mobility disability before the age of 85, according to a study published by JAMA Internal Medicine, a JAMA Network publication.

The number of women ages 85 years and older in the United States is on the rise with 11.6 million women projected to reach 85 by 2050. Obesity is also on the rise, and obesity is a risk factor for diseases that are prevalent in older women, including cardiovascular disease, diabetes and some cancers, the authors write in the study background.

Eileen Rillamas-Sun, Ph.D., of the Fred Hutchinson Cancer Research Center, Seattle, and colleagues examined whether higher body mass index (BMI) and waist circumference (WC) in older women decreased their chances of living to age 85 without major disease or disability. A healthy weight BMI was 18.5 to less than 25, overweight was 25 to less than 30, and obese was 30 to greater than 40.

The study included 36,611 women from the Women's Health Initiative who were an average 72 years old at baseline. Of the women, 19 percent were classified as healthy, 14.7 percent had prevalent disease, 23.2 percent had incident disease, 18.3 percent had a mobility disability (using crutches, a walker or a wheelchair or a limited ability to walk) and 24.8 percent died.

The study's findings indicate underweight and obese women are more likely to die before the age of 85, while overweight and obese women had higher risks of incident disease and mobility disability. A waist circumference (WC) greater than 88 cm (almost 35 inches) also was associated with a higher risk of early death, incident disease and mobility disability.

Black women who were overweight or who had a WC greater than 88 cm at baseline, and Hispanic women who were obese at baseline had higher risks of incident disease compared to white women who were overweight or who had a WC greater than 88 cm, according to the study.

"Having a healthy BMI or WC was associated with a higher likelihood of surviving to older ages without a major disease or mobility disability," the study concludes. "Successful strategies aimed at maintaining healthy body weight, minimizing abdominal fat accretion, and guiding safe, intentional weight loss for those who are already obese should be further investigated and disseminated."