All measurements are performed in the morning after an overnight fast. Height is measured to the nearest 0.5 cm using a wall-mounted stadiometer, and weight is measured using a balance beam scale with subjects in their underwear. Waist circumference is measured at the mid-level between the lower rib margin and the iliac crest. Body composition is assessed by bio-impedance analysis (BIA) and fat mass percentage is calculated using the formula of Deurenberg. Visceral abdominal adipose tissue (VAT) and subcutaneous abdominal adipose tissue (SAT) are determined by a 64-slice computerized tomography (CT) scan at the L4-L5 level (slice thickness 0.6mm).