Researchers at the University of California Berkeley studied fatal car crashes, and used driver's license information to categorize drivers based on their weight.
They found obese adults were twenty percent more likely to die in a car crash than normal weight adults.
Drivers who were extremely obese were fifty percent more likely to die.
The researchers are not sure why this increased risk exists -- but they suspect vehicle design and the fact obese adults likely have worse health than others may play a role.
Experts say the increased risk for death stayed strong even after they accounted for other factors like the age and sex of the driver, seat-belt use and air bag deployment.