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This 5-day diet helped Crohn’s patients feel better fast

A simple 5-day monthly diet tweak may ease Crohn’s disease symptoms and inflammation.

Date:

April 3, 2026

Source:

Stanford Medicine

Summary:

A new clinical trial suggests that what people eat could finally offer real relief for Crohn’s disease, a condition that has long lacked clear dietary guidance. Researchers found that a “fasting-mimicking diet” — involving just five days a month of very low-calorie, plant-based meals — led to noticeable improvements in symptoms for most participants. Even more striking, the diet didn’t just make patients feel better; it also reduced key biological markers of inflammation linked to the disease.

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A short monthly fasting-style diet helped many Crohn’s patients feel better and reduced inflammation markers in a new study. Credit: Shutterstock

"What should I eat?" is one of the most common questions people with inflammatory bowel disease ask their doctors.

It is also one of the hardest to answer. Inflammatory bowel disease, which includes ulcerative colitis and Crohn's disease, has not been studied extensively when it comes to diet. Large, well-controlled studies on dietary changes have been limited.

Now, researchers from Stanford Medicine and collaborating institutions may be closing that gap. In a national randomized controlled trial, they found that a short-term, calorie-restricted eating plan led to meaningful improvements in both symptoms and biological markers in people with mild-to-moderate Crohn's disease. The results were recently published in Nature Medicine.

Studying diet is challenging. Participants may not always accurately report what they eat, and placebo effects are difficult to avoid since people know which diet they are following. Even so, the results stood out. Patients not only reported feeling better, but also showed measurable reductions in inflammation in biological samples. The findings could help doctors give clearer dietary guidance to patients.

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

Crohn's Disease and Limited Treatment Options

Crohn's disease is a long-term condition that affects roughly one million Americans. It causes inflammation in the digestive tract and can lead to symptoms such as diarrhea, cramping, abdominal pain and weight loss.

For mild cases, steroids are currently the only approved treatment. However, they can cause serious side effects, especially when used over long periods.

How the Fasting Mimicking Diet Was Tested

The clinical trial followed 97 patients with mild-to-moderate Crohn's disease across the United States. Of these, 65 participants followed a fasting mimicking diet, while 32 continued with their usual eating habits as a control group. The study lasted three months.

Those in the fasting mimicking group reduced their calorie intake for five consecutive days each month, consuming roughly 700 to 1,100 calories per day. During this period, they were given plant-based meals. For the rest of the month, they returned to their normal diet.

Significant Symptom Improvement

By the end of the study, about two-thirds of the participants following the fasting mimicking diet reported improvement in their symptoms.

"We were very pleasantly surprised that the majority of patients seemed to benefit from this diet," Sinha said. "We noticed that even after just one FMD cycle, there were clinical benefits."

In contrast, fewer than half of those in the control group experienced symptom improvement. Researchers noted that these changes were likely due to natural fluctuations in the disease and ongoing standard treatments, such as medications.

Some people in the fasting mimicking group reported fatigue and headaches, but no serious side effects were observed.

Measurable Reductions in Inflammation

The researchers also looked beyond symptoms to understand what was happening inside the body.

Sinha's interest in the fasting mimicking diet came from earlier research showing it could lower levels of C-reactive protein, a marker of inflammation, in people with elevated baseline levels. "The effects seen on inflammatory markers made this an appealing diet to study in Crohn's disease since many patients with this disease also have elevated inflammatory markers," he said.

To explore this further, the team collected and analyzed biological samples, including blood and stool, to track changes in inflammation.

"Our goal in collecting these and other biospecimens was to dig deeper into why there's this differential response," Sinha said. "Can we find mechanisms to explain the findi