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Obese drivers more likely to die in car accidents, study finds

Being obese may put you at greater risk for dying in a car crash, according to new research.

More than one-third of U.S. adults are obese, according to the Centers for Disease Control and Prevention. Obesity has been linked to heart disease, stroke, Type 2 diabetes and certain types of cancer. Now, researchers say that it also may be a factor in fatal motor vehicle accidents.

"This adds one more item to the long list of negative consequences of obesity," lead author, Thomas M. Rice, an epidemiologist with the Transportation Research and Education Center of the University of California, Berkeley, told the New York Times. "It's one more reason to lose weight."

Researchers analyzed data from the U.S. Fatality Analysis Reporting System (FARS) for 1996 to 2008. A total of 57,491 road traffic collisions were recorded during this time period.

They looked at accidents in which two passenger vehicles were involved, where the most influential component in the death of one or both of the drivers was the impact of the crash. In selected 3,403 pairs of drivers that had similar weights, ages, seat belt use and air bag deployment were selected. About half the drivers -- 46 percent -- were at a normal weight, 33 percent were overweight and about 18 percent were obese. Two-thirds of drivers were male, and about one in three were between the ages of 16 and 24. In addition, one in three drivers did not use a seat belt properly, and the airbag deployed in only 53 percent of the cases.

After looking at the data, researchers found that people who had a World Health Organization classification of obesity level I (people with a BMI of 30.0 to 34.9) were 21 percent more likely to die than normal weight drivers. Those in obesity level II (BMI of 35 to 39.9) were 51 percent more likely to die, and those with the highest level, obesity III (BMI of 40.0 or greater), were 80 percent more likely to die from the accident than normal weight drivers.

Obese women were at a greater risk of dying from the crash, with those with obesity level I having a 36 percent higher chance of experiencing a car crash fatality. The number jumped to twice as likely for people in obesity level II and III respectively.

Underweight men were also more likely to die in a collision compared to normal weight people.

What explains the added risk?

The researchers believe the lower body of obese drivers is pushed forward further on impact before the seat belt reaches the pelvis because of the extra soft tissue, while the upper body is kept restrained. This stops the driver from moving forward, which may cause fatal injuries, according to the researchers.

While obese drivers may have greater health problems that may cause their death and should try to lose weight, the researchers also said that car design may have to change to protect these drivers.

"Vehicle designers are teaching to the test -- designing so that crash-test dummies do well," Rice said. "But crash-test dummies are typically normal size adults and children. They're not designed to account for our nation's changing body types."

Dr. David Katz, director of the Yale University Prevention Research Center, said to HealthDay that it make sense that car manufactures should adjust their products since people's body shapes are changing.

"We have a serious and pernicious problem of anti-obesity bias in the United States. Efforts to address that may at times invite us to pretend that size doesn't matter, but, in fact, it does," he said.

The study was published online on Jan. 21 in the Emergency Medicine Journal.

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