Crash test dummies are getting fatter so they better represent the expanding waistlines and bigger rear ends of American drivers.

Humanetics, one of the leading manufacturers of the dummies in the U.S. and worldwide, developed a new model that better mimics the country's population. About 35 per cent of Americans are considered obese.

"We put into action a new crash test dummy that was representative of that," Chris O'Connor, the company's president and CEO, said in an interview.

'The obese dummy is very important to make sure safety is there for everyone.' - Chris O'Connor, President and CEO, Humanetics

The old dummies were based on statistics from the 1980s, O'Connor said, and represented someone who is 169 pounds with a body mass index of about 25. The new dummy for sale to car manufacturers represents someone who is 270 pounds with a body mass index of 35.

"We're not here to judge who drives but what we do want to do is make sure that everybody is safe and right now, a car designed to a smaller crash test dummy is just not as safe for a larger occupant," he said.

Studies have found that obese drivers are at an increased risk of death compared to average-sized ones. Humanetics took the statistics seriously and wanted to do something in response.

One study, published by the University at Buffalo in 2010, found that morbidly obese people were 56 per cent more likely to die in a crash than normal weight individuals. Moderately obese people were 21 per cent more likely to die.

Studies show increased risks for obese drivers

"The rate of obesity is continuing to rise, so it is imperative that car designs are modified to protect the obese population, and that crash tests are done using a full range of dummy sizes," the lead researcher, Dietrich Jehle, noted at the time. "If they represented our overweight American society, there could be further improvements in vehicle design that could decrease mortality."

Fat crash test dummy

This is the new, bigger, crash test dummy that has been developed by Humanetics in response to an American population that is one-third obese. (Humanetics)

Seatbelt positioning on obese people is one reason they may not survive a crash. A seatbelt is supposed to fit snugly against the pelvis, but in the obese population it doesn't operate the same way. Researchers have also theorized that heavier people could be flung from a car with greater force than lighter people. Pre-existing obesity-related illnesses may also affect a person's ability to recover from injuries sustained in an accident.

Another study from the University at Buffalo in 2012 found that obese drivers are less likely to wear seatbelts than normal weight drivers and that puts them at increased risk of injury or death in the event of a crash.

O'Connor said it makes sense to make dummies more representative of the population and that it will lead to safer vehicles.

"If we have 35 per cent of our population that is obese and they're driving, certainly we want to make sure they are safe. I think we all know a neighbour, friend, relative, or we can speak of ourselves to say why shouldn't we be safe in these cars, as safe as anyone else?" he said.

O'Connor did point out obesity is not just an American or North American problem, noting that China and India also have rising obesity rates.

"The obese dummy is very important to make sure safety is there for everyone," he said.