BACKGROUND AND AIM: We evaluated the association of obesity with serum total antioxidant capacity (TAC), in a population-based sample of 3042 adults. METHODS AND RESULTS: During 2001-2002 we randomly enrolled 1514 men (18-87 years old) and 1528 women (18-89 years old), from the Attica area in Greece into the study, and the sample was stratified by the age-sex distribution of the region (census 2001). Among several variables we also measured serum TAC and weight, height, waist and hip circumferences. Waist circumference greater than 102 cm for men and 88 cm for women was considered an indicator of central fat. METHODS AND RESULTS: Mean waist circumference was 98+/-13 cm in men and 84+/-22 cm in women (P<0.001), while mean hip circumference was 106+/-28 cm in men and 103+/-13 cm in women (P<0.001). Central fat prevailed in 53% of men and 45% of women (P<0.001). Male participants with central fat exhibited 5% lower TAC concentrations compared to leaner individuals (214+/-35 vs. 226+/-33 micromol/L, P=0.04) and female participants with central fat exhibited 7% lower TAC concentrations (256+/-38 vs. 239+/-27 micromol/L, P=0.03). Similarly, obese or overweight male participants had 6% lower TAC concentrations compared to normal weight (217+/-33 vs. 234+/-39 micromol/L, P=0.03) and female obese or overweight participants had 10% lower TAC concentrations (226+/-32 vs. 250+/-30 micromol/L, P=0.02) compared to the others. CONCLUSIONS: Our results suggest an inverse relationship between body fat, central adiposity and antioxidant capacity, irrespective of age and various other potential confounders, namely smoking, physical activity, dietary habits, blood pressure, glucose levels, and lipid concentrations.