U.S. researchers say dialysis patients with low body fat are at increased risk of death.

The study confirmed a direct, linear relationship between body fat and mortality risk with the higher the body fat, the greater the survival.

Using near-infrared interactance technology, the researchers measured body fat percentage in 671 hemodialysis patients from eight California dialysis centers. The researchers then compared five-year mortality rates for patients at different levels of body fat percentage.

The mortality rate was highest for dialysis patients with less than 10 percent body fat -- 2.5 to 3 times higher than for those with body fat of 20 percent to 30 percent. The increased risk of death for patients with very low body fat remained after adjustment for age, sex, race, other illnesses and key laboratory results.

"Our study indicates that body fat may be protective in dialysis patients," the researchers said in a statement. "The results add to the increasing number of reports about the 'obesity paradox' or 'reverse epidemiology' in patients with chronic kidney disease and other chronic diseases."

The finding was presented at the 42nd annual meeting of the American Society of Nephrology in San Diego.