New research from the Canadian Community Health Survey indicates that both obese and underweight individuals run the greatest risk of disability in old age.

As the population continues getting older each year, the rate of functional disability and other physical limitations increases. Efforts to promote wellness, functional autonomy, and health are becoming more and more important as a consequence.

Previous research indicates that functional limitations are linked to changes in body weight in older adults. Most of this research has focused narrowly on the upper-tier of weight; examining the relationship between weight gain, obesity, and physical functioning. What is less understood is whether or not underweight older adults or older adults who experience rapid weight loss are also at an increased risk for disability or diminished physical functioning.

This particular study utilized a sample of over 21,000 adults ages 65 years and older. The researchers analyzed data including self-reported height and weight, body mass index (BMI), a measure of Instrumental Activities of Daily Living (IADL), and various demographics (i.e., age, gender, ethnicity, socioeconomic status, etc.).

In addition to finding that both underweight and obese older adults have a significantly greater chance of developing some form of disability, the researchers also found some interesting demographic patterns. Their results indicate that women, the poor, and those not living with a partner are at increased risk for disability. The odds of decreased physical functioning increase with age.

In academic jargon, this U-shaped relationship between body weight and disability in old age has important wellness implications. Weight loss is a positive thing for older adults who are obese; however, proves to be too narrow a focus for individuals of normal or who are underweight.

Source: Gadalla, T. 2010. Relative body weight and disability in older adults: Results from a national survey. Journal of Aging and Health 22: 403-418.