Obese older adults may be more likely than their thinner peers to suffer a potentially disabling fall -- though the most severely overweight may be somewhat protected from injury, according to a U.S. study.
Falls are often seen as a problem for thin, frail older adults, since their bones are especially prone to fractures, but obesity carries its own risks, said researchers whose findings appeared in the Journal of the American Geriatrics Society.
"People who are obese may have a harder time with balance," said Christine Himes, of Syracuse University in New York, who worked on the study.
And when obese older adults lose their footing, they may be less able to react quickly and stop a fall, she added.
Looking at 10,755 people aged 65 and up, Himes and colleague Sandra 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.
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 -- about 45 kg (100 lb) overweight for a man, or 36 kg (80 lb) overweight for a woman.
Body mass index is a measure of weight against height.
The study participants 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 linked to both obesity and the risk of falling, such as arthritis, pain in the legs, diabetes and stroke. But obesity itself was still linked to a higher fall risk.
But when it came to the risk of being injured by a fall, the most severely obese older adults, with a BMI of 40 or higher, were one-third less likely to be injured than normal-weight people who fell.
People with milder obesity had no such protective effect. In fact, those moderately obese people were at greater risk of reporting longer-term disabilities after falls, versus normal weight men and women.
Those with 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.
Himes said the patterns make sense.
Obese people, in general, may be more vulnerable to falls than thinner folk, and when they do fall, the most obese people may get some protection from injury by their extra padding and denser bones.
But when obese people are injured, they may be less likely to recover.
"It's just harder for obese people to recover from injury. They're going to be in poorer physical shape to begin with," Himes said.
It's estimated that more than one-third of U.S. residents 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.
"This is just another reason that obesity needs to be considered an important public health problem," she said.