Fasting-Mimicking Diet Elicits Clinical, Biochemical Response in Mild Crohn’s Disease

New research is shedding light on the benefits of a short-term, calorie-restrictive diet for patients with mild to moderate Crohn’s disease.1,2

Findings from the national, randomized controlled clinical trial showed 5 days of a fasting-mimicking diet (FMD) per month resulted in high rates of clinical response, clinical remission, and biochemical response, superior to those achieved with baseline diet.1,2

According to the US Centers for Disease Control and Prevention, the US prevalence of inflammatory bowel disease (IBD) is estimated to be between 2.4 and 3.1 million. Crohn’s disease is estimated to affect about 1 million of these individuals.3

While recent therapeutic advances have introduced new treatment options for patients with moderate to severe Crohn’s disease, including the 2025 US Food and Drug Administration approvals of guselkumab and mirikizumab, steroids remain the only approved therapy for mild Crohn’s.4,5

Given the known side effects associated with long-term use of steroids, alternative approaches to disease management have become a focal point of research for this patient population, with dietary modifications being among the most popular.1,2

“We have been very limited in what kind of dietary information we can provide patients,” Sidhartha Sinha, MD, an assistant professor of gastroenterology and hepatology at Stanford and the senior author on the paper, said in a statement.2 “This study will give physicians evidence to support recommendations in an area that patients are very curious about.”

The Effects of an Intermittent Reduced Calorie Diet on Crohn's Disease study was an open-label, randomized, controlled, clinical trial comparing the effectiveness of FMD versus baseline diet to reduce clinical disease activity in patients with mild-to-moderate CD. The study enrolled adult patients 18-70 years of age with CD who had mild-to-moderate symptoms, defined by a Crohn’s Disease Activity Index (CDAI) score > 150 and ≤ 450.1

Between 2019 and 2023, 97 out of 279 patients screened in a national recruiting campaign were randomly assigned in a 2:1 ratio to either FMD or control. A total of 65 participants were assigned to the FMD group and 32 were assigned to control.1

Patients in the FMD group consumed a fasting-mimicking diet for 5 consecutive days per month for 3 consecutive months. For the remaining days in each month, patients consumed their regular baseline diet. Patients in the control group continued their baseline diet.1

The primary outcome of clinical response was a reduction in CDAI of > 70 points or CDAI ≤150 after the third 5-day diet cycle.1

Investigators noted baseline characteristics of the enrolled participants were generally well-balanced between the groups, with the FMD group having a greater proportion of females (80.0% vs 56.3%) compared to control. The median age was 45.0 years (interquartile range [IQR], 35.0 to 55.0). Baseline median CDAI was 196 in the FMD group and 195 in the control group.1

Participants in the FMD group achieved 76.9% adherence to the diet for all 3 cycles, with similar adherence rates observed across each of the 3 cycles. In the control group, 87.5% of participants were adherent to their baseline diet during the study period.1

In intention-to-treat analysis, a significantly greater percentage of participants achieved the primary outcome clinical response 70 in the FMD group compared to control (69.2% FMD versus 43.8% control; P = .03). The median decline in CDAI was -105 (IQR, -48 to -155) for the FMD group compared to -76 (IQR, 0 to -119) for control (P = .02).1

A total of 42 patients in the FMD group (64.6%) and 12 patients in the control group (37.5%) achieved the prespecified secondary outcome of clinical remission after 3 cycles of treatment (P = .02).1

Of note, after completing the first cycle of FMD, investigators pointed out more participants achieved clinical response 70 (66.2% vs 43.8%; P <.05) and clinical remission compared to participants who made no diet changes (60.0% vs 37.5%; P = .04).1

They additionally observed a significant decline from baseline in fecal calprotectin in the FMD group compared to the control group (-22.0% vs 8.0%; P = .03). In post hoc analysis, a significantly greater proportion of participants in the FMD group experienced a ≥50% reduction in fecal calprotectin compared to the control group (37.3% vs 6.8%; P = .03).1

Exploratory analyses of plasma metabolites and peripheral blood mononuclear cell gene expression revealed post-FMD decreases in key inflammatory lipid mediators and immune-effector transcripts, concordant with reduced CD activity.1

“There’s still a lot more to be done to understand the biology behind how this and other diets work in patients with Crohn’s disease,” Sinha said.2

References

1. Kulkarni C, Fardeen T, Gubatan J, et al. A fasting-mimicking diet in patients with mild-to-moderate Crohn’s disease: a randomized controlled trial. Nat Med. https://doi.org/10.1038/s41591-025-04173-w

2. Stanford Medicine. A new diet option for mild-to-moderate Crohn’s disease. January 13, 2026. Accessed January 13, 2026. https://med.stanford.edu/news/all-news/2026/01/crohns-disease-diet.html

3. US Centers for Disease Control and Prevention. IBD Facts and Stats. June 21, 2024. Accessed January 13, 2026. https://www.cdc.gov/inflammatory-bowel-disease/php/facts-stats/index.html

4. Brooks A. FDA Approves Mirikizumab (Omvoh) for Crohn’s Disease. HCPLive. January 15, 2025. Accessed January 13, 2026. https://www.hcplive.com/view/fda-approves-mirikizumab-omvoh-for-crohn-disease

5. Campbell P. FDA Approves Guselkumab (Tremfya) For Crohn Disease. HCPLive. March 20, 2025. Accessed January 13, 2026. https://www.hcplive.com/view/fda-approves-guselkumab-tremfya-for-crohn-disease