A study in the United States has found the most obese drivers are more likely to die after a car crash than other drivers.
After analysing 3400 fatal collisions, researchers from the University of California found very obese people are 80% more likely to be killed.
They said car designs should be changed to make them safer for such people.
Previous research showed seatbelts don't work as well on obese drivers as with other drivers.
The emergency department at Wellington hospital, New Zealand, said the findings were not surprising because obese people have more momentum in a crash and are also harder to assess and treat.