People who become overweight or obese significantly increase their risk of type 2 diabetes, heart disease, and stroke, but their expanded waistline could spell even more trouble when they’re behind the wheel. A study out of the Erie County Medical Center’s Department of Emergency Medicine found that obese people who were involved in a car accident were less likely to wear their seat belt and, subsequently, more likely to suffer from fatal injuries.

"Not buckling up is a deadly decision," said lead researcher Dr. Dietrich Jehle. "Obese drivers are far less likely to wear seatbelts than are drivers of normal weight, which puts them at a greater risk of being subjected to higher impact forces and being ejected from the vehicle, both of which lead to more severe injury and/or death."

Jehle and his colleagues from Erie Medical Center used the Fatality Analysis Reporting System that tracked drivers involved in a motor vehicle crash, which led to loss of life between 2003 and 2009. Each driver involved in the fatal car accident was grouped by the World Health Organization's (WHO) obesity definition by body mass index (BMI) — BMI of 30 or more is considered obese.

After collecting data from close to 200,000 car crashes in which at least one person was fatally injured, people who exceeded the WHO’s guidelines for obesity were 67 percent less likely to be wearing a seat belt compared to people in the normal weight category, Reuters reported. Previous research performed by Jehle and colleagues from the University of Buffalo determined that obese people were also 56 percent more likely to die in major car crashes compared to their normal weight counterparts.

“We found that the relationship between the amount of obesity and seatbelt use was linear: The more obese the driver, the less likely that seat belts were used,” Jehle said in a statement from the previous study. “The question is: What can we do to cars to make them safer for the obese? How can we make it more likely for people, including the overweight or obese, to wear seatbelts?”

According to the Centers for Disease Control and Prevention, fatal motor vehicle accidents are the leading cause of death among Americans between the ages of 5 and 34. Over 2.3 million adult passengers and drivers were treated at emergency rooms around the U.S. following a car crash back in 2009. The following year in 2010, it was reported that 19 states had not adopted primary enforcement seat belt laws — a police officer can pull a driver over and issue a ticket if someone in the vehicle is not wearing a seat belt.

Source: Jehle G, Consiglio J, Karagianis J, Doshi C, Jehle D. Obesity and seatbelt use: a fatal relationship. American Journal of Emergency Medicine. 2014.