Older adults who are obese are more likely to develop problems with day-to-day activities, such as bathing, getting dressed, and going to the bathroom, a new study finds.

The more excess weight they are carrying, the more likely they are to report new disabilities, according to surveys of more than 20,000 adults 65 and older.

Interestingly, being overweight did not appear to bring a higher risk of death—except in the very heaviest -- making this one more study to suggest that moderate weight gains don't have the same impact on older people's health as they do in the general population, said study author Dr. Christina Wee of Beth Israel Deaconess Medical Center in Boston.

As a result, Wee told Reuters Health, some experts assume that the benefits from weight loss are smaller, or perhaps non-existent, in older adults. Furthermore, losing weight could be dangerous in the elderly, for instance if it causes malnutrition or bone loss, she added. "So it was not clear that, on balance, the benefits (of weight loss) would necessarily outweigh the risks."

To further investigate how carrying excess weight specifically impacts the elderly, Wee and her team reviewed information collected from 20,975 Medicare recipients during periodic interviews over a 4-year period. More than one-third of participants were overweight, and another 18 percent were obese. All participants were followed for 14 years in order to note who died.

The study focused on people's responses to questions about their ability to complete day-to-day activities, which include eating, getting in and out of chairs, and walking. The researchers separated these basic motions from so-called "instrumental" daily activities, which consisted of using the telephone, cooking, shopping, and managing money.

Reporting in the Annals of Internal Medicine, the authors found that between 22 and 32 percent of overweight and obese women, for instance, reported they were struggling more with at least one daily activity over the course of the study period, versus 20 percent of older women who were at a healthy weight.

When it came to "instrumental daily activities," between 30 and 38 percent of overweight and obese men said those activities had become harder since the study began, while only 28 percent of men without excess weight reported the same problem.

Extra weight appeared to be less associated with developing problems in daily activities among African-Americans, although their number (8 percent of the study group) was too small to be sure about the finding.

It's not clear why excess weight may have a more obvious impact on disability than on the risk of death, Wee noted. One explanation might be the presence of a "survival effect," she said, in which obese adults who live to 65 or older may be more "resistant" to death, perhaps carrying genes that help combat the effects of obesity. "But older adults are already more prone to disability and obesity might just tip the scales even more."

Indeed, the participants with the lowest risk of dying during the study period were those considered to be overweight, not obese. This finding is not particularly surprising, Wee noted, people's weight classes were determined using body mass index, which is not as accurate a measurement of body fat in the elderly as in adults in general, she said. "In addition, since many chronic illnesses in the elderly (may) lead to unintentional weight loss, being thinner may be a sign of having a lot of illnesses."

For now, it's not clear exactly what older adults who are carrying excess body fat should do about it, she noted. Their focus may not need to be on dieting, she said, but on preserving their ability to perform daily activities. "It may be the treatment is not just to lose weight (but) to get physical or exercise therapy to strengthen muscles and improve function."