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Posted on Wed, Feb 10, 2010 : 11:27 a.m.

Overweight men have higher chance of surviving a car crash, University of Michigan study finds

By Tina Reed


Men who are overweight have a higher chance of surviving a car crash if they're wearing a safety belt, a University of Michigan study found.

The U-M Transportation Research Institute study found men who were overweight had a 22 percent lower chance of being killed in a fatal crash than men who are underweight.

But the opposite was true if overweight weren't buckled in. According to the study, men with a body mass index between 35 and 50 were 10 percent more likely to be killed in an auto accident.

The researchers were analyzing data of more than 300,000 drivers involved in fatal crashes in the U.S. between 1998 and 2008 from the National Highway Traffic Safety Administration.

Female drivers are 1.1 times more likely than male drivers to die in a fatal traffic crash. There was no statistically significant link between a female driver's BMI and likelihood of dying in a crash due to being belted in.

Overall, drivers who don't wear safety belts are 2.1 times more likely to die in a fatal crash than those who are belted.

The researchers suggested design of airbags, safety belts, knee restraints and seats might need to be redesigned to protect people who have extreme BMIs.

"At a similar BMI, men are generally heavier than women because of height differences. Therefore, a man is more likely to overload the airbag, resulting in the increase in risk with increasing BMI for unbelted men. The decrease in risk with increasing BMI for belted men is likely because the safety belt tends to prevent this overloading," Michael Sivak, research professor and head of UMTRI's Human Factors Division, said in a release.

The results were published in the current issue of the journal Traffic Injury Prevention.

Tina Reed covers health and the environment for You can reach her at, call her at 734-623-2535 or find her on Twitter @TreedinAA.


Old Salt

Thu, Feb 11, 2010 : 11:41 a.m.

Well isn't this just wonderful..and what did this study cost us taxpayers

Tina Reed

Thu, Feb 11, 2010 : 11:36 a.m.

The study defined a "fatal" crash as one that involved at least one or more fatalities. This particular study looked specifically at the link between driver survival rates in these types of crashes and body mass index and seat belt use. The journal Traffic Injury Prevention has also published articles from other authors about crash outcomes when considering the vehicle model and year as well as the the crash injury risks for obese occupants. One thing I found interesting from the results of this study was the conclusion about what this study implies for safety design in vehicles: "The increased risk for obese unbelted males and belted males as well as for underweight belted males and females, relative to their normal BMI counterparts, suggests that the designs of airbags, safety belts, knee restraints, seats and other components of occupant restraint systems may need to be improved to better protect occupants at both extremes of BMI." In other words, most vehicle safety systems don't appear to be tailored to those who have a terribly low or a terribly high BMI. The study goes on to suggest those testing the safety of vehicles would do well do make changes to the size of crash-test dummies to not only represent occupants with normal BMI's, but to also represent people at either extreme of the weight scale.


Wed, Feb 10, 2010 : 9:24 p.m.

EG, your question of course poses another one. What are their chances of surviving a non-fatal crash? This should be where the real research happens!

Lon Horwedel

Wed, Feb 10, 2010 : 7:50 p.m.

Maybe the study should have gone further to see if the obese are involved in more accidents than physically fit drivers due to slower reflexes, or steering wheels that are interfered with by the driver's girth, etc. Think about it, when's the last time you saw an overweight NASCAR or Formula 1 driver???


Wed, Feb 10, 2010 : 4:44 p.m.

I tracked down the journal article (Survival in Fatal Road Crashes: Body Mass Index, Gender, and Safety Belt Use, available to UoM folks though the library: It's impossible to draw the conclusions that the article implies. Imagine there's a crash with one or more vehicles. Someone died in one of the vehicles. The odds of survival favor those who are buckled up and overweight. It could be a result of biological factors, sure, but that's not clear from the study. But, there's no accounting for the make/model of vehicle. It seems _incredibly_ likely that big people drive bigger cars and are therefore more likely to survive an accident. Or it's possible that women favor smaller cars. Or that unbelted obese people are likelier to be poor/uneducated and to be driving a junker. FWIW, this also is only looking at survivability in fatal accidents. It doesn't tell you whether fat or thin people are more likely to be involved in a fatal accident in the first place. In other words, you can't say that a normal weight person is overall more likely to be killed in a car accident than a large person. In the future, could you publish links to journal articles (or even just the NAME of the article) so we can have a look at them ourselves? Any Ann Arborite who works for the University can access most journals online. I'd also like to know whether science articles are based on someone reading a press release or delving into the actual journal article. MOST science claims are later disproved and it's usually obvious from the get go that a study is iffy. This one certainly is.


Wed, Feb 10, 2010 : 1:17 p.m.

This is great news and just in time for Fat Tuesday!

Tina Reed

Wed, Feb 10, 2010 : 12:38 p.m.

Thanks, Sally! That fix was made.


Wed, Feb 10, 2010 : 12:15 p.m.

Tina. Oops! In paragraph 2, that would be "overweight" rather than "overweigh."


Wed, Feb 10, 2010 : 12:12 p.m.

That is because we have a built in airbag.


Wed, Feb 10, 2010 : 12:11 p.m.

Great, give obese people a reason to not get healthier.

dading dont delete me bro

Wed, Feb 10, 2010 : 11:57 a.m.

finally! a benefit of being bmi challenged.