'Spare Tire' Might Protect Men During Car Accident

By Randy Dotinga HealthDay Reporter
New research suggests that a few extra pounds can be good for you -- if you're male and unlucky enough to be in a car accident, that is.

Moderately overweight males are more likely to survive serious car accidents than either the thin or the very fat. Apparently, a bit of extra padding -- but not too much -- provides extra protection, according to the study.

The research suggests that there's "a threshold, a cut-off point," where overweight suddenly becomes dangerous instead of protective, noted study lead author Dr. Shankuan Zhu, an assistant professor in the Department of Family and Community Medicine at the Medical College of Wisconsin.

For reasons that aren't clear, women don't get the same protection from extra weight: Being fat, thin or in-between didn't affect their likelihood of dying in a car accident, the study found. Researchers have made similar links between weight and car accident fatality rates in the past, but the new study is the first to take a significant look at gender differences.

The researchers examined reports of 22,107 accidents in the United States involving drivers aged 16 and older from 1997 to 2001. The study findings appeared online Wednesday and will be published in the April edition of the American Journal of Public Health.

Overall, males were about twice as likely to die as females -- 0.87 percent of them died in the accidents, compared to 0.43 percent of females.

The researchers then looked at the connection between death rates and the body mass indexes (BMI) of the accident victims. BMI measures whether a person's height and weight are proportionate, with a BMI of 30 being the statistical threshold for obesity.

Fatalities among males became increasingly likely as their body mass indexes dipped below 22 (meaning they're on the thin side) or above 35 (meaning they're obese).

The results suggest that a moderate layer of fat -- such as that found in overweight but not obese people -- provides a "cushioning" effect during a crash, Zhu said.

But the cushion effect may vanish in males who are obese because their medical problems -- such as cardiovascular diseases and high-blood pressure -- could make them more vulnerable to dying from the effects of a crash, Zhu said.

The same might be true for thin males, who may have medical problems that exacerbate their ability to survive a crash, said Dr. Saman Arbabi, director of trauma surgery research at the University of Michigan. He co-authored a similar study that found nearly identical results.

Why would body weight affect fatality rates in men but not in women? Arbabi suggested that it may have something to do with the physics of car accidents and the way that fat appears on the body. Overweight men tend to look like apples, with weight around their bellies, while overweight women look like pears, with fat around their hips and buttocks.

These weight patterns may simply provide more protection for men, Arbabi said, adding that more research is needed to confirm that. For now, he said, men should realize there's yet another reason to lose weight: while "love handles" might prove helpful in a crash, being too fat will be of no help at all.

SOURCES: Shankuan Zhu, M.D., Ph.D., assistant professor, division of research, Department of Family and Community Medicine, Medical College of Wisconsin, Milwaukee; Saman Arbabi, M.D., M.P.H., assistant professor, surgery and director, research, Division of Trauma Surgery, University of Michigan, Ann Arbor; April 2006, American Journal of Public Health