Obesity increases your risk for heart disease, diabetes, and some cancers. Being obese puts pressure on your joints and gives you lung capacity. Now researchers in Los Angeles say there's another, somewhat less intuitive risk of being obese: the risk of dying from injuries.

What the researchers wanted to know: Are obese patients more likely to die from blunt trauma?

What they did: The researchers looked at records on every person who came into the surgical intensive care unit at one L.A. trauma center in 2002. For each person, they calculated body mass index (BMI), which is a way to measure body weight while taking height into account. A BMI over 30 is considered obese. Most of the people were injured in car accidents or were pedestrians hit by cars.

What they found: Obese people were twice as likely to die, even though obese patients and nonobese patients had similar patterns of injuries. Nearly a third of obese patients died, compared to 16 percent of nonobese patients. The researchers don't know why this is—maybe the obese people who died had other problems like high blood pressure. Or maybe the body's normal inflammatory response to injuries has a worse effect on obese people. The researchers also mention that obese people are just harder to work on—radiology isn't as accurate, surgery is harder, and keeping airways clear is tougher, too.

What the study means to you: This looks like yet another risk of obesity. Since no one knows why obese people seem to be more likely to die of their injuries, it's hard to prevent it, other than by losing weight.

Caveats: Several studies have looked at the relationship between obesity and injury and found different results, so this question is not closed yet.

Find out more: A body mass index calculator

The National Institute of Diabetes and Digestive and Kidney Diseases explains obesity and some of the causes and risks.

Read the article: Neville, A.L., et al. "Obesity Is an Independent Risk Factor of Mortality in Severely Injured Blunt Trauma Patients." Archives of Surgery. September 2004, Vol. 139, pp. 983–987.

Abstract online: http://archsurg.ama-assn.org