Everyone knows that being overweight increases your risk of heart disease, diabetes, and some types of cancer, but new research reveals that even normal-weight people aren't scot-free. A European study suggests that people with belly fat -- even if they're at a healthy weight -- have a higher risk of dying during a 10-year period than their same-weight peers without a spare tire. The report was published Wednesday in the New England Journal of Medicine.

Research participants with a higher BMI were at greater risk of dying during the 10-year study.

"I was surprised that even people who would be considered normal weight in terms of their [body mass index] have a higher risk of death if their waist circumference is increased," says Tobias Pischon, M.D., the study's lead author and a member of the department of epidemiology at the German Institute of Human Nutrition (DIfE).

In one of the largest long-term prospective studies in the world, a team of researchers at the European Prospective Investigation Into Cancer and Nutrition analyzed 359,387 people ages 25 to 70 from nine European countries. Watch more on the study results »

The researchers found that those with a higher body mass index (BMI) were at a greater risk of dying during the 10-year study than normal-weight people. Health.com: Compare more than 40 diet plans

But when they looked at waist circumference and waist-to-hip ratio alone -- not just overall weight -- they found that those factors were strongly associated with a higher mortality risk too. A 2-inch increase in waist circumference raised the mortality risk by 17% in men and 13% in women, regardless of BMI. The link was strongest in those who were at a healthy weight, compared to their heavier peers. Health.com: Why getting rid of belly fat may lower Type 2 diabetes risk

Men with the biggest girths (about 40.4 inches) were 2.05 times more likely to die during the study than men with waists that were less than 33.9 inches. Women with waists 35 inches or larger had a mortality risk 1.78 times higher than those with waists less than 27.6 inches.

It's been known for some time that belly fat is bad for one's health, and it has been linked to a greater risk of erectile dysfunction, memory problems, diabetes, and heart disease, among other health issues. Abdominal fat -- unlike fat elsewhere in the body -- can pad internal organs; it is thought to promote inflammation by releasing hormones.

Previous studies have noted the link between being overweight and the risk of developing a chronic disease, but the extent of abdominal fat's role was controversial. The current study clarifies that role by providing "very reliable conclusions," says Hans-George Joost, M.D., DIfE's scientific director.

The study has, in fact, been larger and broader than most, according to Leah Whigham, Ph.D., a nutritional scientist at the University of Wisconsin -- Madison. "The waist-to-hip ratio or waist circumference might be particularly important for people at the low end of the [BMI] spectrum," she says.

Still, there's hope if you have an apple-shaped figure. A 2003 study suggested that increased dietary fiber and weight training can slim the waistline if they're coupled with a reduction in trans-fatty acids and sedentary activities such as television viewing. Health.com: Dietary fats can help -- or harm -- your heart

Whigham recommends regular exercise, even if people don't seem to shed pounds from their overall weight. "There are some people who no matter how hard they try, they aren't going to get their weight down that low," she says. If you're significantly overweight, incorporating regular exercise into your daily routine can help reduce your waist-to-hip ratio, which might help add years to your life.

Enter to win a monthly Room Makeover Giveaway from MyHomeIdeas.com

Copyright Health Magazine 2009

All About Obesity