['Acute pancreatitis (AP) is a systemic inflammatory disease. It is already known that obesity and central fat distribution are related to the severity of AP, but the intimate mechanism of this relationship remains unknown. Obesity and central fat distribution are associated with an inflammatory state that could amplify the systemic inflammatory response (SIR) in AP. The aim of this study was to investigate how obesity and body fat distribution correlate with the SIR and severity of AP.', '85 consecutive patients with AP were studied. Body mass index, body fat distribution and previous comorbidity were obtained at admission. The SIR was assessed by the serum levels of interleukin (IL)-1beta, IL-1ra, IL-6, IL-8, IL-10, IL-12p70, tumor necrosis factor-alpha (TNF-alpha) and C-reactive protein. Serum concentrations of the previously mentioned cytokines were also determined in a control group of 40 healthy volunteers.', '63 patients (74%) had mild AP and 22 patients (26%) had severe AP. All the cytokines except IL-12p70 and TNF-alpha were increased in the AP group in comparison with the control group. The SIR was significantly increased in patients with severe AP. Obese patients and patients with central fat distribution had significantly more comorbidity, a higher proportion of severe AP and more intense SIR. Patients with comorbidity had a significantly higher proportion of severe AP and more SIR.'] Do obesity and fat distribution imply a greater systemic inflammatory response and a worse prognosis in acute pancreatitis?