Living with a pouch
Has anyone actually studied fasting for pouchitis?
The short answer is no. Two reviews of the diet research in ileoanal pouches turn up no study of fasting at all. Here is what has been tested nearby, including one randomised trial that came out positive, and why it was not about pouches.
4 min read7 sources
Two reviews have gone looking for what diet research exists in people with an ileoanal pouch. A 2025 systematic review in Inflammatory Bowel Diseases gathered 24 studies. A 2024 review looked specifically at diet and microbiota modulation for chronic pouchitis. Between them they cover elemental diets, exclusion diets, the Mediterranean pattern, low FODMAP, fibre supplements, calcium, a green tea derivative and ten separate probiotic studies.
Neither contains a study of fasting, intermittent fasting or time-restricted eating. Not a negative one. Not a small one. The question has not been asked of a pouch.
What fasting has been tested on
A 2023 review in Therapeutic Advances in Gastroenterology searched for intermittent fasting in inflammatory bowel disease. It found four publications: three randomised controlled trials in animal models of colitis, and one prospective observational study in people.
The one study in people
The human study followed 80 people with inflammatory bowel disease fasting during Ramadan. No differences were found in any measure except one: a statistically significant increase in the median partial Mayo score in ulcerative colitis. The increase was greater in those who were older, or who had a higher baseline faecal calprotectin. The single human signal pointed, mildly, toward more disease activity rather than less.
The reviewers concluded that given the limited evidence, it is difficult to draw conclusions regarding the effects of intermittent fasting on body weight, inflammation or disease activity. They called for large randomised trials in patients with active disease before it goes anywhere near routine management.
Then a trial arrived
A randomised pilot trial has now tested time-restricted feeding in Crohn’s disease. Thirty-five people completed it, eating inside an 8-hour window with 16 hours fasting, six days a week, for 12 weeks, against standard management. The results went the right way. Body mass index fell by 0.9 and visceral adipose tissue by 194 cubic centimetres. Faecal calprotectin was maintained or reduced, and serum amyloid A, leptin, adipsin and plasminogen activator inhibitor-1 all fell. The control group trended the other way, including a rise in interleukin-6.
The version that was tested, and did not work
Not eating has been studied in inflammatory bowel disease before, in its most complete form: bowel rest, with nutrition given intravenously. In active Crohn’s disease, a randomised trial put 51 people into three groups: intravenous nutrition with nothing by mouth, a formula diet by tube, or partial intravenous nutrition alongside unrestricted food. Remission at 21 days was 71, 58 and 60 percent. The authors concluded that bowel rest was not a major factor in achieving a remission during nutritional support, and that it did not influence outcome during one year’s follow-up.
In severe acute ulcerative colitis the answer was the same. Two British randomised trials in the 1980s added intravenous nutrition to intravenous steroids. Complications related to that nutrition went up. Colectomy and mortality rates did not improve. Resting the bowel was a reasonable theory that was tested properly and did not hold.
Where this came from
That 24 studies of dietary interventions and supplementation in people with an ileal pouch-anal anastomosis were identified, covering dietary patterns, specific foods, fibre and other supplements and probiotics, with no study of fasting, intermittent fasting or time-restricted eating among them.
Gold S, Levinson C, Colombel JF, Manning L, Sands BE, Kayal M, “Dietary Interventions and Supplementation in Patients With an Ileal Pouch–Anal Anastomosis: A Systematic Review”, Inflammatory Bowel Diseases, 2025;31(1):246–258That the dietary approaches studied in chronic pouchitis are the elemental diet, the Crohn’s disease exclusion diet, the Mediterranean diet, low FODMAP and the Monash pouch diet, with no mention of fasting, intermittent fasting, time-restricted eating or bowel rest.
Puca P, Del Gaudio A, Becherucci G, et al., “Diet and Microbiota Modulation for Chronic Pouchitis: Evidence, Challenges, and Opportunities”, Nutrients, 2024;16(24):4337That four publications on intermittent fasting in inflammatory bowel disease were found — three randomised controlled trials in animal models of colitis and one prospective observational study in patients; that the human study of 80 people fasting during Ramadan found no differences in any measure except a statistically significant increase in the median partial Mayo score in ulcerative colitis, greater in those older or with higher baseline faecal calprotectin; and that given the limited evidence it is difficult to draw conclusions regarding effects on body weight, inflammation or disease activity, with large randomised trials in active disease needed.
Lavallee CM, Bruno A, Ma C, Raman M, “A review of the role of intermittent fasting in the management of inflammatory bowel disease”, Therapeutic Advances in Gastroenterology, 2023;16:17562848231171756A randomised pilot trial of time-restricted feeding in Crohn’s disease with overweight: 35 completers, a 16:8 schedule six days a week for 12 weeks, with body mass index falling 0.9, visceral adipose tissue falling 194 cubic centimetres, faecal calprotectin maintained or reduced, and serum amyloid A, leptin, adipsin and plasminogen activator inhibitor-1 all significantly decreased, against opposite trends including rising interleukin-6 in the standard management group; and the inclusion criterion of a body mass index above 25.
Haskey N, Lewis AG, Lavallee C, et al., “Time-restricted feeding improves inflammatory and metabolic biomarkers in Crohn’s disease with overweight: a randomized, placebo-controlled pilot trial”, Journal of the Canadian Association of Gastroenterology, 2025;8(Suppl 1):i31A randomised trial of 51 people with active Crohn’s disease comparing total parenteral nutrition with bowel rest, a defined formula diet by tube, and partial parenteral nutrition with unrestricted food; remission at 21 days of 71, 58 and 60 percent; and the conclusion that bowel rest was not a major factor in achieving a remission during nutritional support and did not influence outcome during one year’s follow-up.
Greenberg GR, Fleming CR, Jeejeebhoy KN, Rosenberg IH, Sales D, Tremaine WJ, “Controlled trial of bowel rest and nutritional support in the management of Crohn’s disease”, Gut, 1988;29(10):1309–1315That two UK-led randomised trials in the 1980s using total parenteral nutrition as an adjunct to intravenous steroids in acute severe ulcerative colitis showed an increase in nutrition-related complications but no improvement in colectomy or mortality rates.
Honap S, Jairath V, Sands BE, et al., “Acute Severe Ulcerative Colitis Trials: the Past, the Present, and the Future”, Gut, 2024;73(10):1763–1773That output should not be regulated by cutting down on fluids, because of the risk of dehydration.
IA and the RCN Gastroenterology and Stoma Care Nursing Forum, “Going Home — for all-round support with an internal pouch”, 6th edition