BACKGROUND: Colonic diverticulitis is correlated with age, body mass index (BMI), and increased visceral or subcutaneous fat. Obesity contributes to diverticulosis, diverticulitis and its complications onset, as visceral fat activates inflammatory pathways that exacerbate these conditions. The aim of this study was to evaluate the association of visceral adiposity and BMI on complications of acute colonic diverticulitis. METHOD: A prospective cohort study was conducted on patients with acute diverticulitis admitted to the general surgery ward of a university hospital in Istanbul from September 2017 to February 2022. A total of 208 patients were classified into uncomplicated and complicated diverticulitis per the World Society of Emergency Surgery guidelines. After documenting demographic, clinical, and laboratory data, along with BMI and computed tomography measurements of visceral and subcutaneous fat areas (VFA, SFA), we conducted a statistical analysis to assess the relationships between VFA, SFA, and BMI in both groups. RESULTS: Complicated diverticulitis group was found to have significantly lower values of BMI and VFA (p = 0.037 and p = 0.046 respectively). Similarly, BMI and VFA values of patients who underwent all interventional procedures including percutaneous drainage and surgery were found to be significantly lower than the conservative treatment group (p = 0.007, p = 0.025 respectively). V/S <
0.68 is an independent predictor in the complicated group. CONCLUSION: Our study shows that complicated diverticulitis cases have lower BMI and visceral fat area. We suggest that increased visceral adipose tissue may serve a protective role by preventing these diverticula from developing into more complicated forms. Therefore, visceral adiposity metrics can be integrated in the predictive analyses.