Did you hear about renowned Harvard scientist Barbara Kahn's latest published research? I blogged about it recently. Kahn and colleagues state, in a report published in Cell Metabolism (July 2007), that it's possible to use a simple blood test to detect the presence of a specific protein called RBP4. Kahn et al say the presence of RBP4 can be used to measure accumulations of deep belly fat. Underpinning this research is a belief that such accumulations of belly fat increase risk for metabolic syndrome, leading to various maladies including heart disease and diabetes.

However, not everyone accepts this point of view. A Yale research team says that deep belly fat may not be so evil after all. The researchers, who are based at Yale University School of Medicine in Chevy Chase, Maryland, assert that metabolic syndrome is caused not by belly fat but by insulin resistance in skeletal muscle. This resistance, they state, makes it tough for the body to manufacture glycogen, so - in people who are insulin resistant - energy that cannot be stored as glycogen gets diverted into fatty acid production, which then contributes to metabolic syndrome.

The team compared abdominal fat levels in young and healthy individuals, some of whom were insulin sensitive and some of whom were insulin resistant. The result? "There is absolutely no difference in the volume of abdominal fat," states Yale's Gerald I. Shulman, who was lead author of the study. Abdominal fat, says Dr. Shulman, "may come later in the course of the disease [metabolic syndrome], but it's not a primary, underlying factor."