Healthy body weight throughout life prevents onset of physical disability later in life

May 22 2007

Maintaining a healthy body weight throughout adulthood may help prevent or delay the onset of physical disability as we age, according to researchers from Wake Forest University School of Medicine and colleagues.

The study, reported on-line by the International Journal of Obesity, found that older adults with a history of excess weight in midlife or earlier had worse physical performance than those who were normal weight throughout adulthood or became overweight in late adulthood.

"The data suggest that interventions to prevent overweight and obesity in young and middle-age adults may be useful in preventing or delaying the onset of physical disability later in life," said Denise K. Houston, Ph.D., R.D., lead author and an instructor in internal medicine-gerontology.

While the association between current obesity and physical disability is well-known, the cumulative effect is not. Using data from the Health, Aging and Body Composition (Health ABC) study, researchers examined the association between weight history and physical performance in late adulthood.

Participants were recruited from 70- to 79-year-old Medicare-eligible residents in the Pittsburgh, Pa., and Memphis, Tenn., metropolitan areas. Participants were eligible only if they reported no difficulty walking one-fourth of a mile, climbing 10 steps, or performing basic activities of daily living. They also had to be free of life-threatening illness.

The body mass index (BMI) of 2,803 participants was calculated using recalled height and weight at ages 25 and 50 and measured height and weight at ages 70 to 79. A body mass index of 30 or greater is considered obese. Overweight is defined as having a BMI between 25 and 30.

Participants, physical performance was assessed with a short battery of tests to measure walking speed, ability to rise from a chair, and balance. Walking endurance was measured with a timed 400-meter walk. Poor physical performance is a predictor of future disability, nursing home admission and mortality.

The researchers found that men and women who were obese at ages 25 years, 50 years and between 70 and 79 years had significantly lower scores of physical performance than those who were normal weight at these ages. Women who were overweight, but not obese, at these ages also had lower performance. In addition, men and women with a history of being either overweight or obese in midlife or earlier had worse physical performance than those who didn't become overweight or obese until late adulthood.

Houston said there are several explanations for the findings.

"Obesity may lead to joint wear and tear, reduced exercise capacity, and a higher rate of chronic diseases such as cardiovascular disease, diabetes, and arthritis that can result in physical disability," she said. "Obesity in young and middle adulthood may result in earlier onset of chronic diseases and lower physical activity, contributing to decreased muscle strength and cardiovascular fitness and greater declines in physical performance."

The data were adjusted to account for factors such as smoking, education, age, race and level of physical activity at baseline that could have influenced the results.

Houston said the results are significant because the elderly U.S. population is growing and is expected to double by the year 2030 to about 20 percent.

"Over the past couple of decades there has been a trend towards declining rates of disability in older adults. However, the dramatic increase in overweight and obesity in the U.S. may reverse these declines and may lead to an increase in disability among future generations of older adults as well as contribute to an increase in disability among middle-age and younger adults," she said.