Epicardial Fat and Weight Loss

Increased visceral fat or "ectopic" fat deposition is associated with insulin resistance and increased cardiovascular risk.

Traditionally, the term visceral fat has been used to describe the omental and mesenteric fat located inside the abdomen. Over the last several years, this concept has been expanded to include other "ectopic" fat depots including the liver and the heart.

Recognition that the fat located around the heart can be a marker of visceral fat was pioneered by Gianluca Iacobellis, who joined me as a clinical research fellow a few years ago at McMaster University and has since been recruited to their faculty.

In this month's issue of OBESITY, Iacobellis reports on work we collaborated on just before I left McMaster to relocate to the University of Alberta demonstrating that epicardial fat is a sensitive marker of changes in visceral fat associated with weight loss.

In this study in 20 severely obese subjects who underwent a 6-month very low calorie diet weight loss program resulting in a 20% loss of original body weight, waist circumference decreased by 23% whereas epicardial fat thickness decreased by 32% of baseline.

Based on this finding, we suggest that measurement of echocardiographic epicardial fat thickness may provide an additional tool in understanding the metabolic risk associated with variation in fat distribution. Perhaps, more importantly, echocardiographic measurement of epicardial fat can serve as a simple and relatively inexpensive tool to assess changes in visceral fat with weight loss (or gain) in clinical practice.

Certainly beats simply measuring waist circumference (a rather crude surrogate measure of intra-abdominal fat) or the rather more expensive CAT or MRI study.

AMS
Edmonton, Alberta

p.s Thanks to Navneet Singh and Sean Wharton for their great help with this study and to all the patients who volunteered their time for these measurements