Belly fat blues

That bulge is the outward sign of a deeper problem: visceral fat, a kind of biological monstrosity that, in excess, wreaks havoc on the body, raising the risk for heart disease, diabetes, possibly even dementia and some types of cancer.

Lying deep inside the body, wrapping around the liver and other major organs, visceral fat acts like a kind of organ itself -- spewing out bad hormones and squashing the production of good ones. It sets up the body for sickness as the years roll by and additional fat accumulates.

"Visceral fat is very bad for you," says Richard N. Bergman, a professor at USC's Keck School of Medicine. "It seems to have a more negative outcome on health than overall fat."

The evidence now is so compelling that some experts suggest it's time to forget about scales and weight loss and focus on waists and "inch loss."

Luckily, visceral fat doesn't appear to be a particularly stubborn enemy. Health experts have discovered that consistent, moderate exercise by itself appears to help the body rid itself of vast amounts of deep abdominal fat -- even when the scales show the pounds aren't dropping very fast.

This emerging science carries a message for consumers: Measure your waist circumference. And reduce it if need be. Doing something about that paunch could help save your life.

Recent studies on visceral fat help explain a well-established fact: that having a pear shape is more healthful than having an apple shape. A pear shape is caused by subcutaneous fat resting just under the skin. Apple is caused by the deep, visceral fat. What this means is that although both types of people -- apple and pear -- can be overweight, the person with the apple shape has more health risks.

It also means that people with normal weight can be at a higher health risk without realizing it.

Most people gain abdominal fat with age, but research shows the tendency to put on weight around the middle may be inherited. A study published this month in the Proceedings of the National Academy of Sciences identified particular genes that appear to dictate how fat develops and where it's stored.

A long list of illnesses

Meanwhile, the evidence for visceral fat's ill effects is mounting.