Not All Belly Fat Is Bad for the Heart

July 21, 2011 -- A new study shows that where a person stores body fat may be more important for heart disease risk than how big they are.

Doctors have long wondered why some obese people appear reasonably healthy, while others seem to be on a path toward heart disease and type 2 diabetes.

Fat that’s stored around the internal organs, which is called visceral fat,  has been thought to play a role in that difference. 

Waist size is a rough measure for the amount of visceral fat a person has.

But newer studies have suggested that visceral fat may not deserve the blame.

Newer imaging techniques have shown that fat that's stored in muscle and organs like the liver may contribute to unhealthy levels of blood fats, says Faidon Magkos, PhD, a research assistant professor of medicine in the department of nutrition at Washington University in St. Louis.

Fat Storage in the Liver and High Triglycerides

The study looked at two groups of 14 obese men with waist sizes over 37 inches.

The first group had high levels of blood fats called triglycerides, which are thought to contribute to heart disease. The second group had normal triglyceride levels.

A third group of 10 normal-weight men, with normal triglyceride levels, was used for comparison.

Researchers in Sweden and Finland used specialized imaging techniques to measure how much fat was stored inside the men’s livers and how much fat was stored in the body cavity around their organs and also underneath their skin.

Previous research has suggested that fat that’s stored around the organs, called visceral fat, may play a role in the development of heart disease.

But the study found that men with high triglyceride levels and men with normal levels had about the same amounts of visceral fat.

Where the men were really different, it turns out, was their livers.

Men with high triglycerides had nearly twice as much fat stored in their livers as did men with normal triglyceride levels, 13% and 6.9% fat, respectively. The livers of non-obese men were about 2.9% fat.

“What this suggests is that the deposition of fat in the liver may change the liver in a way that makes the liver do bad things for the heart,” says Scott R. Sherron, MD, a cardiologist with the Texas Heart Institute in Houston, who was not involved in the research.

In the meantime, experts say the advice to people who are carrying extra pounds is to exercise and lose weight.

The study is published in the journal Arteriosclerosis, Thrombosis, and Vascular Biology.