Obese older adults may be more likely than their thinner peers to suffer a potentially disabling fall -- though the most severely obese may be somewhat protected from injury, a new study suggests.

Falls are often seen as a problem for thin, frail older adults, since their bones are especially prone to fracture.

But obesity carries its own risks, according to Christine L. Himes, one of the researchers on the new study.

"People who are obese may have a harder time with balance," said Himes, of Syracuse University in New York.

And when they lose their footing, she told Reuters Health, obese older adults may be less able to react quickly and stop a fall.

In their study, Himes and colleague Sandra L Reynolds found that obese older adults were anywhere from 12 percent to 50 percent more likely to suffer a fall over two years than their normal-weight peers were.

Those odds rose with the level of obesity. The 50-percent higher risk was seen among people with a body mass index (BMI) of 40 or higher -- or about 100 pounds overweight for a man, and 80 pounds overweight for a woman.

The findings, reported in the Journal of the American Geriatrics Society, are based on 10,755 Americans age 65 and up who were surveyed every two years.

Between 1998 and 2006, the group reported a total of 9,621 falls, resulting in more than 3,100 injuries serious enough to need medical attention.

Of people who suffered a fall, 23 percent were obese, compared with just under 20 percent among older adults who did not fall during the study period.

The researchers factored in health conditions that are linked to both obesity and the risk of falling -- like arthritis, pain in the legs, diabetes and stroke. But obesity itself was still linked to a higher fall risk.

When it came to the risk of being injured from a fall, the most severely obese older adults -- a BMI of 40 or higher -- were one-third less likely to be injured than normal-weight people who fell. People with milder obesity, however, showed no such protective effect.

In fact, those moderately obese people were at greater risk of reporting longer-term disabilities after fall, versus normal-weight men and women.

Over the eight-year study, participants reported 4,324 instances of new or worsened disabilities after a fall -- though, Himes noted, it's not certain that the fall caused the problem.

People with milder obesity (a BMI of 30 to 34.9) were 17 percent more likely than normal-weight people to report a disability after a fall. And those with a BMI between 35 and 39.9 were 39 percent more likely to report a disability.

Those patterns make sense, according to Himes. Obese people, in general, may be vulnerable to taking a spill than thinner folks. And when they do fall, Himes said, the most obese people may get some protection from injury by their extra padding and denser bones.

But when obese people who are injured, they may be less likely to get better.

"It's just harder for obese people to recover from injury," Himes said. "They're going to be in poorer physical shape to begin with."

So fall and disability prevention, she said, may be one more reason for people to maintain a healthy weight as they age. "This is just another reason that obesity needs to considered an important public health problem," Himes noted.

Besides losing weight, obese older people may want to be especially mindful of cutting their fall risk in other ways. In general, experts recommend regular moderate exercise like walking and tai chi to improve balance and coordination; getting rid of fall hazards in your home, like loose rugs or any other obstacle you might trip over; and using assistive devices such as grab bars for the tub or shower.

It's estimated that more than one-third of Americans age 65 and up suffer a fall each year. And a similar proportion of older adults are obese -- a trend, Himes noted, that is likely to get worse.