Role of Visceral Fat in Metabolic Syndrome: Implications for Treatment and Prevention Eric S. Freedland, M. D. (Boston, MA) There are likely many scenarios and pathways that can lead to metabolic syndrome. This paper reviews mechanisms by which the accumulation of visceral adipose tissue (VAT) may contribute to the metabolic syndrome, and explores the paradigm of a critical VAT threshold (CVT). Exceeding the CVT may result in a number of metabolic disturbances such as insulin resistance to glucose uptake by cells. Metabolic profiles of patients with visceral obesity may substantially improve after only modest weight loss that could reflect a significant reduction in the amount of VAT relative to peripheral or subcutaneous fat depots, thereby maintaining VAT below the CVT. The CVT may be unique for each individual, which may help explain the phenomena of apparently lean individuals with metabolic syndrome, the so-called metabolically normal weight (MONW), as well as the obese with normal metabolic profiles, i.e., metabolically normal obese (MNO), and those who are "fit and fat." The concept of CVT may have implications for prevention and treatment of metabolic syndrome. The identification of the CVT is admittedly difficult and its anatomical boundaries are not well-defined. Thus, the CVT will continue to be a work in progress.