5-Day Diet Improves Crohn’s Disease Symptoms, Study Finds

A five-day-a-month fasting-mimicking diet may offer relief for adults with mild to moderate Crohn’s disease, according to a new clinical trial led by Stanford Medicine. The diet, which involves a plant-based, low-calorie meal plan, appears to reduce both symptoms and inflammation associated with the chronic condition.

The study, published in Nature on February 26, 2026, is the largest randomized controlled trial of an oral diet intervention in Crohn’s disease to date. Researchers found that 69% of patients following the fasting-mimicking diet (FMD) achieved clinical response – defined as a reduction in Crohn’s Disease Activity Index (CDAI) of at least 70 points or a CDAI of ≤150 – after three cycles of the five-day diet. 64.6% achieved clinical remission.

What is Crohn’s Disease?

Crohn’s disease is a chronic inflammatory condition affecting the digestive tract. The immune system mistakenly attacks parts of the digestive system, leading to symptoms like abdominal pain, diarrhea, fatigue, and unintended weight loss. The disease typically follows a cyclical pattern of flares and periods of remission.

While medications are often effective, treatment options are limited for those with milder forms of the disease. Currently, there are no FDA-approved therapies for long-term maintenance in mild cases beyond steroids, which can have significant side effects.

How Does the Fasting-Mimicking Diet Work?

The fasting-mimicking diet is designed to temporarily shift the body into a “fasting-like” metabolic state while still allowing individuals to consume food. It’s a plant-based, low-calorie meal plan followed for five consecutive days each month, with patients returning to their regular diet for the remainder of the time.

Sidhartha Sinha, MD, assistant professor of medicine in the Division of Gastroenterology and Hepatology at Stanford, led the trial. He noted the rarity of high-quality diet studies in Crohn’s disease, despite the strong interest from both patients and healthcare providers.

Study Details and Results

The randomized controlled trial involved 97 participants. Those in the FMD group followed the diet for five consecutive days per month for three months. The primary outcome measured was clinical response, and secondary outcome was clinical remission.

Forty-five patients in the FMD group (69.2%) and 14 patients in the control group (43.8%) met the primary outcome of clinical response (P = 0.03).

Nature

Forty-two patients in the FMD group (64.6%) and 12 patients in the control group (37.5%) achieved the secondary outcome of clinical remission (P = 0.02).

Nature

Researchers also observed a decline in fecal calprotectin, an inflammatory marker, in the FMD group compared to the control group (−22.0% versus 8.0%, P = 0.03). Exploratory analyses revealed decreases in key inflammatory lipid mediators and immune-effector transcripts following the FMD, suggesting a link between the diet and reduced disease activity.

Implications and Future Research

The findings suggest that the fasting-mimicking diet could be a valuable adjunctive therapy for managing mild to moderate Crohn’s disease. The study supports further investigation into the diet’s potential benefits for chronic inflammatory diseases.

The clinical trial was registered on ClinicalTrials.gov under the identifier NCT04147585.

While the results are promising, it’s important to note that this study focused on individuals with mild to moderate Crohn’s disease. Further research is needed to determine the diet’s effectiveness in patients with more severe cases and to understand the long-term effects of this dietary approach.