Background: Patients with inflammatory bowel disease (IBD) consider that their diet is important for controlling symptoms and frequently ask their physician for additional guidance on this matter. The objectives of the present study of patients with IBD were to characterize the prevalence of exclusion diets and fasting and to identify associated risk factors. Methods: Using an anonymous questionnaire, we screened patients attending our IBD nutrition clinic between November 2021 and April 2022 for exclusion diets. The avoidance of a food category completely was defined as total exclusion and avoidance most of the time was defined as partial exclusion. We also asked patients whether they fasted totally, intermittently, or partially. Result: A total of 434 patients with IBD were included. On inclusion, 159 patients (36.6%) totally excluded at least one food category and 271 (62.4%) partially excluded at least one food. Intermittent, total, or partial fasting was reported by 30.8% of the patients. Disease activity (odds ratio (OR) [95% confidence interval] = 1.7 [1.1-2.7], p = 0.0130) and treatment with a small-molecule or an investigational drug (OR = 4.0 [1.5-10.6], p = 0.0059) were independently associated with an exclusion diet. A history of stenosis (OR = 2.0 [1.2-3.2], p = 0.0063) and active disease (OR = 1.9 [1.2-3.1], p = 0.0059) were associated with fasting. Conclusion: In this real-world study, approximately two-thirds of our patients with IBD reported the partial or total exclusion of at least one food category and one third reported fasting. A systematic nutritional evaluation might improve clinical management and quality of care for patients with IBD both Crohn's disease and ulcerative colitis. Olivier Bonsack and Bénédicte Caron contributed equally to this manuscript.