January 15, 2003

It's bad enough worrying about the fat we see. Now we have to worry about invisible fat as well. Researchers at the Fred Hutchinson Cancer Research Center have discovered that "intra-abdominal fat," wrapped around our internal organs, is linked to higher incidence of chronic disease, including heart disease, diabetes and certain cancers. Even thin people may have this fat lurking inside them.

Women tend to accumulate it after menopause. Men put it on even more easily, since they tend to attract fat to their middles, while many women put it on their hips. External fat around the middle is one sign you may be harboring hidden fat, although the only way to tell for sure is to have an MRI or a CT scan. That's the bad news.

The good news is that moderate exercise can reduce invisible fat, even if it doesn't appear to be making a difference on the outside. That means taking the battle of the bulge undercover could help save your life.

"Regardless of the amount of weight lost, we now know that exercise reduces hidden intra-abdominal fat, the most dangerous type of fat," said Dr. Anne McTiernan, a Fred Hutchinson researcher and lead author of a study on this topic published today in the Journal of the American Medical Association.

McTiernan and her colleagues at the University of Washington, Yale University and the University of Colorado randomly assigned 173 sedentary postmenopausal women to two groups. One group did regular, moderate exercise for a year, and the other participated only in a stretching program. Three-quarters of the participants had enough intra-abdominal fat to put them at risk.

At the end of the year, the group that exercised more vigorously had reduced intra-abdominal fat by between 3.4 percent and 6.9 percent, while maintaining their calories. Although they lost an average of just three pounds, it was still enough to reduce their risk of cancer and other diseases, she said.

"The bottom line is even if you're not seeing changes from exercising, you are getting the benefits," she said. "It's never too late to enjoy the health benefits of exercise." The women in the stretching group, on the other hand, had a modest increase in intra-abdominal fat. Bernyce Edwards, 70, who was in the moderate exercise group, said she's become a fervent believer in the benefits of staying fit.

After spending years in sedentary work for United Airlines, she watched the pounds creep on, a little each year. But her 42-year-old daughter's death from breast cancer spurred her to participate in breast cancer research.

"I was frustrated and angry," Edwards said. "I wanted to do whatever I could."

She signed up for the study. Now, more than a year later, she still does aerobics and lifts weights three times a week at her local YWCA, and walks the beach at Alki at least once a week. She's dropped nearly 20 pounds and kept it off.

"I feel so much better," she said. "And it makes me think more clearly."

She's also pleased it's helping cut her risk of disease and hopes it will prompt others to stick with their exercise programs.

Having intra-abdominal fat is bad for several reasons. It's linked to higher cholesterol levels, which increases heart disease. Intra-abdominal fat also tends to increase insulin levels, which promotes the growth of certain cancers. For women, it increases the risk of breast and colon cancer, McTiernan said. It's unclear yet how the fat affects men's health, since the study looked only at postmenopausal women.

But the fat is also linked to increased risk of heart disease and diabetes, diseases that plague men as well.

The findings add one more reason to keep weight under control. Women, especially, tend to put on a pound or two a year, which adds up, the researcher said.

"If someone's gaining weight and their pants are getting tighter, the odds are they have intra-abdominal fat," she said. "People with high levels of intra-abdominal fat may not even know it."