Belly Fat a Greater Health Risk Than Obesity, Mayo Study Says

Here’s another reason to fret over a flabby stomach.

A new study suggests that adults who aren’t technically overweight but have a lot of fat around their guts run a higher death risk than people who are obese.

Conducted by researchers at the Mayo Clinic in Rochester, Minn., the study looked at people with normal body mass index scores who also fit the definition for “central obesity” — meaning they had a high waist-to-hip ratio.

Normal-weight patients with a lot of belly fat, it turned out, had the highest death risks from cardiovascular disease and other causes, according to a study presented Monday, Aug. 27, at a scientific meeting in Europe.

“We knew from previous research that central obesity is bad, but what is new in this research is that the distribution of the fat is very important even in people with a normal weight,” said Dr. Francisco Lopez-Jimenez, a Mayo Clinic cardiologist. “Central obesity in the setting of normal weight appears to be more dangerous than any other fat distribution pattern.”

Central obesity is measured by comparing the circumference of a patient’s stomach to a circumference of the hips. When the stomach measurement is 90 percent or more of the hip measurement in men, and 85 percent or more of the hip measurement in women, a patient generally is thought to have a worrisome distribution of fat.

Stomach fat could be riskier because it’s associated with insulin resistance and other health problems, researchers said. Plus,

the health risk of a high waist-to-hip ratio might also be a function of narrow hips, since fat in that location is presumed to have protective effects, Lopez-Jimenez said.

The results shouldn’t be interpreted as an endorsement of obesity. Instead, they further Lopez-Jimenez’s argument that the body mass index — a ratio of weight to height that’s commonly abbreviated as BMI — is not always the best indicator of health risks caused by excess weight.

“Most of the national campaigns for weight control and obesity focus on BMI,” he said. “If the message is, ‘You’re OK if your BMI is OK,’ that’s a problem. … We see from time to time people who have a big belly, but their body weight is normal. Some will be very content and not excited about starting an exercise program, even if they need it.”

The study included data on body measurements, socioeconomic status and illness history for some 12,785 people age 18 and older. Researchers calculated baseline data and grouped people into one of six categories depending on two variables: whether they had high or low waist-to-hip ratios; and whether their body mass index scores put them at normal weight, overweight or obese levels.

Researchers calculated mortality rates for study participants over a follow-up period that typically spanned about 14 years. During the period, there were about 2,562 deaths, of which 1,138 were related to cardiovascular problems.

The risk of cardiovascular death was 2.75 times higher, and the risk of death from all causes was 2.08 times higher, in people of normal weight with central obesity versus those who had a normal BMI score and a normal waist-to-hip ratio.

Although the magnitude wasn’t so large, normal weight people with central obesity also had a higher death risk than obese people in the study.

Resistance training and regular aerobic exercise are two parts of the solution to central obesity, Lopez-Jimenez said. By building muscle mass, “that’s going to very likely redistribute the shape of the body,” he said.

Last year, Mayo Clinic researchers published a study showing that patients with both coronary artery disease and central obesity had up to twice the risk of dying as heart disease patients with more petite paunches.