Is visceral fat involved in the pathogenesis of the metabolic syndrome? Human model.

OBJECTIVE: To review the evidence for and against the role of visceral adipose tissue as a major contributor to the metabolic complications of obesity through abnormal regulation of lipolysis. RESEARCH METHODS AND PROCEDURES: Data from investigators in the field who have studied visceral adiposity and metabolic health and/or regional and systemic free fatty acid (FFA) release were considered. RESULTS: Although visceral fat mass was positively correlated with adverse health consequences and excess FFA availability, visceral fat was not the source of excess systemic FFA availability. Upper body non-visceral fat contributes the majority of FFAs in lean, obese, diabetic, and non-diabetic humans. Increasing amounts of visceral fat probably result in greater hepatic FFA delivery. DISCUSSION: Systemic, as opposed to hepatic, insulin resistance is unlikely to be caused by high rates of visceral adipose tissue lipolysis.