Belly fat may be more dangerous for the heart than obesity

No one would mistake a beer gut for a sign of health.

But a new study finds that carrying extra pounds around the middle can be dangerous even for people with an overall healthy weight.

In a 14-year study of more than 15,000 people, normal-weight men with big bellies were twice as likely to die compared to men who were obese. Women with normal weights and big bellies were 32% more likely to die during the study than obese women, according to the study, led by Francisco Lopez-Jimenez, a Mayo Clinic cardiologist.

“Often times, we think if we’re a normal weight, then we’re OK,” said Leslie Cho, head of preventive cardiology at the Cleveland Clinic, who wasn’t involved in the new study, published in Annals of Internal Medicine. “But weight is not as important as your level of fitness and where you hold your fat.”

So just how big a belly is considered risky?

People can calculate their waist-hip ratio by dividing their waist measurement by their hip measurement, Lopez-Jimenez said.

Men have “central obesity” if their waist-hip ratio is 0.9 or more, according to the World Health Organization. In women, central obesity is defined as a ratio of 0.85 or more.

“Not all fat is equal,” Lopez-Jimenez said.

Just as there are “good” and “bad” types of cholesterol, there are different types of fat, Lopez-Jimenez said. “The fat around the belly might look the same under the microscope as fat from the arms or legs, but it’s much more active,” he said.

Belly fat appears to be especially unhealthy, because it’s often deposited in the liver, where it makes inflammatory substances that contribute to diabetes and heart disease, Lopez-Jimenez said.

The study is a reminder of the limitations of assessing a person’s risk of heart disease or death with only the body mass index, or BMI, Cho said.

The BMI is a ratio of weight and height. A BMI of 18.5 to 24.9 is considered healthy; a BMI of 25 to 29.9 suggests overweight; while a BMI over 30 indicates obesity.

“If you just look at BMI, you’re not getting the whole picture,” said psychologist Martin Binks, a spokesman for the Obesity Society and an associate professor of nutritional sciences at Texas Tech University in Lubbock.

“If someone has 50 pounds of body fat spread all over their body, they have a very different risk profile than if the fat is all in their stomach,” Binks said.

Fat deposited below the belt -- on the legs and buttocks -- appears to offer some protection for the heart, although doctors aren’t sure exactly why, Lopez-Jimenez said.

He said his study suggests that people should be conscious of their waist-hip measurements and strive to build muscle, rather than just shed pounds.

“When people lose weight, some of their weight they lose will be muscle mass, if they don’t exercise,” Lopez-Jimenez said. “If you just lose weight but don’t build muscle, you may not be improving your health that much.”