A new study by Queen's University shows for the first time that visceral fat in the abdomen is directly associated with a higher risk of mortality in men.
According to Physical and Health Education doctoral student Jennifer Kuk, who is the first author of the study, these findings underline the importance of measuring abdominal fat to predict the risk of future disease and mortality. "This reinforces the need to target visceral fat in therapeutic strategies for dealing with obesity," she says. "Body weight alone is not a sufficient indicator of risk."
Since visceral fat is strongly correlated with waist circumference, the researchers recommend that waist measurement be a routine measure in clinical practice. (At present tests of visceral fat are not available for clinicians in Canada.)
The study, supported by grants from the Canadian Institutes of Health Research and the U.S. National Health Institutes, is published in the on-line edition of the international journal, Obesity Research. Also on the research team are Drs. Robert Ross and Peter Katzmarzyk from Queen's School of Physical and Health Education, and Drs. Milton Nichaman, Timothy Church and Steven Blair from the Cooper Institute in Dallas, Texas.
Using computed tomography (CT) images, the researchers acquired slices of the abdomen to measure visceral, subcutaneous and liver fat in 291 men. They found that visceral fat alone independently predicted risk of mortality.
"We're trying to find out which factors are most associated with disease," says Dr. Ross, noting that earlier studies have shown weight is not the most important indicator. "It's possible to exercise and decrease your risk even though weight may stay the same."
When looking at diet weight loss versus exercise weight loss, those who exercise tend to lose more visceral fat and maintain muscle fat better than those using strictly a diet approach, he points out. "This reinforces the importance of maintaining regular physical activity."
Although the current study was restricted to men, excess abdominal fat is a risk factor for women as well, says Ms Kuk. "For both men and women we need to stress the importance of physical activity and measuring your waist. The emphasis of obesity reduction strategies should move away from diet alone and from focusing solely on body weight."