B cell activation factor (BAFF) is a recently discovered member of the TNF ligand superfamily secreted by adipocytes, previously linked to autoimmune and lymphoproliferative disease. The aim of this study was to investigate the relationship between BAFF plasma levels and the non-modified, usual dietary composition as well as obesity-related anthropometric parameters in a cohort of 58 obese and non-obese Central-European Caucasian individuals. We found that BAFF had an independent predictive role for percentage of body fat; moreover, BAFF levels were correlated with waist and hip circumference. BAFF plasma levels were also significantly correlated with investigated dietary composition based on the 7-day food records, as the BAFF levels correlated with the percentage of energy derived from the carbohydrates and with energy derived from the dietary fat. Our results suggest that BAFF may play a role in linking the immune status and metabolic response to diet.