THURSDAY, Dec. 23 (HealthDay News) -- Here's another reason not to pile on too many excess pounds: A new study finds that the obese and very obese are at raised risk of death in severe car crashes.

According to the research, published in the American Journal of Emergency Medicine, a moderately obese driver is 21 percent more likely to die in a severe motor vehicle crash compared to non-obese drivers, while being severely obese hikes the risk of death by 56 percent.

However, being just slightly overweight seemed to lower the odds for death in a severe crash: these drivers were actually less likely to die than either underweight or normal-weight drivers, according to researchers at the University at Buffalo School of Medicine and Biomedical Sciences.

In the study, the researchers analyzed data from the national Fatality Analysis Reporting System involving almost 156,000 drivers in severe motor vehicle crashes occurring between 2000-2005. The researchers included all fatalities occurring within 30 days of a crash.

The link between obesity and death risk was found for both men and women, the researchers noted.

The study's lead author said the findings could have implications for car design and car safety testing.

"The rate of obesity is continuing to rise, so is it imperative that car designs are modified to protect the obese population, and that crash tests are done using a full range of dummy sizes," Dr. Dietrich Jehle, professor of emergency medicine, said in a university news release.

"Extending the range of adjustable seats would be helpful, as well as encouraging moderately and morbidly obese individuals to buy larger vehicles with more space between the seat and the steering column," he said.

"We also recommend that manufacturers design and test vehicle interiors with obese dummies, which currently are not available."

The study was funded in part by the U.S. Federal Highway Administration.

More information

Find out more about safe driving at the U.S. Department of Transportation.