Aliment Pharmacol Ther 2010; 32: 244–253Summary: Background  Obesity increases the risk for severe acute pancreatitis, although abdominal obesity may be a better prognostic marker.Aim  To determine if a single anthropometric parameter best predicts severe acute pancreatitis and correlates with intra‐abdominal fat.Methods  Ninety‐nine patients with acute pancreatitis were studied prospectively. Anthropometry included body mass index (BMI) and girths (umbilical/minimum waist, iliac/trochanter hip, thigh). Several waist‐to‐hip/waist‐to‐thigh ratios (WHR/WTR) were constructed. A CT‐scan with calculation of cross‐sectional abdominal fat areas was obtained in 37 cases.Results  Severe acute pancreatitis occurred in 25 patients. Waist circumference (WC), WHR and WTR – all using the umbilical reference – most accurately predicted severe acute pancreatitis. Only umbilical WC was retained in multivariate analysis: the risk for severe acute pancreatitis increased 16% with every 1 cm (OR 1.16, 95%CI: 1.1–1.3). Abdominal obesity caused a 6‐fold increase in risk. Umbilical WC correlated best with subcutaneous fat area (r = 0.791, P < 0.001), whereas WHR with intra‐abdominal (r = 0.594, P < 0.001).Conclusions  Abdominal obesity according to umbilical WC is a better predictor for development of severe acute pancreatitis than BMI, minimum WC, WHR and WTR. The protocol for anthropometry must be standardized as it may affect results. Both subcutaneous and intra‐abdominal fat appears to affect the likelihood of a severe outcome.