Obese drivers are more likely to die in car crashes than other motorists, scientists have found.

Research shows fat people are propelled further forward during a collision because of their additional soft tissue which prevents a seat belt from tightening immediately against the pelvis.

Scientists now believe car design may have to change to protect overweight drivers.

Analysis of United States collision data found those who were most overweight - in the World Health Organisation obesity category III - were 80% more likely to die in an accident than drivers of a healthy weight.

Those in category II were 51% more likely to be killed in a crash, while the risk was even lower for those in category I, at 21%.

When broken down by gender, obese women were found to be at greater risk than men. Those in obesity category III were almost twice as likely to die on the road than their male counterparts, the scientists said.

Their analysis of more than 3,403 pairs of drivers also showed underweight men were more likely to die in a collision than motorists of a healthy weight.

The authors said: "Findings from this study suggest that obese vehicle drivers are more likely to die from traffic collision-related injuries than non-obese occupants involved in the same collision.

"Education is needed to improve seat belt use among obese people."

The authors, from the University of California and the University of West Virginia, published their findings in the Emergency Medicine Journal.