Five-Day Diet Found to Rapidly Improve Symptoms in Crohn’s Disease Patients, Study Shows

A new clinical trial from Stanford Medicine, published in Nature Medicine, suggests that a short, monthly fasting-style diet may significantly improve symptoms and reduce inflammation in people with Crohn’s disease.

Crohn’s disease is a chronic condition that causes inflammation in the digestive tract, leading to symptoms such as abdominal pain, diarrhea, fatigue, and weight loss. Treatment options remain limited, especially for mild cases, where long-term steroid use can lead to serious side effects. This has made diet an area of growing interest, though evidence has historically been scarce.

In this randomized controlled trial, researchers followed 97 patients with mild-to-moderate Crohn’s disease over three months. Participants were divided into two groups: 65 followed a fasting-mimicking diet (FMD), while 32 continued their usual eating habits. The FMD group consumed a reduced-calorie, plant-based diet—around 700 to 1,100 calories per day—for five consecutive days each month, returning to normal eating for the remainder of the time.

The results were notable. About two-thirds of patients in the FMD group reported improvements in symptoms, compared to fewer than half in the control group. Benefits were observed as early as after the first cycle. While some participants experienced mild side effects like fatigue and headaches, no serious adverse events were reported.

Importantly, the improvements were not just subjective. Biological analysis showed a significant drop in fecal calprotectin, a key marker of gut inflammation. Other inflammatory signals, including lipid mediators and immune cell activity, were also reduced. These findings suggest that the diet may directly influence inflammatory pathways.

Overall, the study provides promising evidence that structured dietary interventions like fasting-mimicking diets could become a valuable tool in managing Crohn’s disease, offering patients a non-drug strategy to complement existing treatments.

REFERENCE: C. Kulkarni, T. Fardeen, J. Gubatan, J. Ye, K. Jarr, E. Dickson, H. Jang, M. Temby, A. Patel, Y. Jiang, G. Singh, K. Keyashian, S. Streett, E. Ho, G. Barber, S. Singh, D. Limsui, N. Anaizi, L. Becker, S. P. Spencer, D. Mehrish, D. Perelman, V. D. Longo, V. Charu, J. F. Ashouri, M. M. Davis, A. Habtezion, J. L. Sonnenburg, C. Gardner, S. R. Sinha. A fasting-mimicking diet in patients with mild-to-moderate Crohn’s disease: a randomized controlled trial. Nature Medicine, 2026; 32 (3): 1023 DOI: 10.1038/s41591-025-04173-w