Carrying extra weight earlier in life increases the risk of developing problems with mobility in old age, even if the weight is lost eventually, says new research out of the Sticht Center on Aging at Wake Forest University School of Medicine, in Winston-Salem, N.C.

The study, funded by the National Institute on Aging and the Wake Forest University Claude D. Pepper Older Americans Independence Center, appeared in the April 15 issue of the American Journal of Epidemiology.

"In both men and women, being overweight or obese put them at greater risk of developing mobility limitations in old age, and the longer they had been overweight or obese, the greater the risk," says lead investigator Denise Houston, an assistant professor of gerontology at the School of Medicine and an expert on aging and nutrition. "We also found that, if you were of normal weight in old age but had previously been overweight or obese, you were at greater risk for mobility limitations."

Houston added that dropping weight later in life can lead to problems with mobility because weight loss later in life is usually involuntary and the result of an underlying chronic condition.

The study is based on data collected in the Health, Aging, and Body Composition study, which enrolled Medicare recipients in Pittsburgh, Pa., and Memphis, Tenn., between April 1997 and June 1998. Participants had to be well-functioning, living in the community, and free of life-threatening illness.

The researchers defined mobility limitation as difficulty walking a quarter-mile or climbing 10 steps. They analyzed information from 2,845 participants who were on average 74 years old. Participants reported no problems with mobility at the beginning of the study. Information on new mobility limitations was collected every six months over seven years of follow-up.

Using participants' body mass index (BMI), a measurement equal to a person's weight in kilograms divided by height in meters squared, at different age intervals, the researchers found that women who were overweight or obese (BMI of 25 or greater) from their mid-20s to their 70s were nearly three times more likely to develop mobility limitations than women who were normal weight throughout. The risk for men was slightly less—they were about 1.6 times more likely to develop mobility limitations, the study says.

The study also found that women who were obese (BMI of 30 or greater) at age 50, but not in their 70s, were 2.7 times more likely to develop mobility limitations compared with women who weren't obese during those years. Men who were obese at 50, but not in their 70s, were 1.8 times more likely to develop mobility limitations than men who never carried the extra weight.

Carrying extra weight can strain joints, hinder exercise, and lead to chronic conditions, such as diabetes, arthritis, and heart disease, that are related directly to the development of mobility limitations, Houston says.

The results are significant, Houston added, because the elderly population in the U.S. 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 physical disability in older adults," Houston says. "However, the dramatic increase in overweight and obesity in the United States may reverse these declines and may lead to an increase in physical disability among future generations of older adults.

The data suggest that interventions to prevent overweight and obesity in young and middle-aged adults may be useful in preventing or delaying the onset of mobility limitations later in life."

Wake Forest University Baptist Medical Center is an academic health system comprised of North Carolina Baptist Hospital, Brenner Children's Hospital, Wake Forest University Physicians, and Wake Forest University Health Sciences, which operates the university's School of Medicine and Piedmont Triad Research Park. The system comprises 1,056 acute care, rehabilitation, and long-term care beds.