Overnight Fasting Cut Crohn’s Symptoms by Half in New Trial

Meal timing may be more important than overall calorie reduction for reducing visceral fat in people with Crohn’s disease.

Illustration by The Epoch Times, Shutterstock

Up to 40 percent of Crohn’s patients don’t respond to the most advanced treatments available—and as many as half who do will eventually stop responding. Researchers have found that even something as simple as an overnight fast could help.

A randomized controlled trial published in Gastroenterology found that time-restricted eating within an 8-hour window and fasting for 16 hours a day, six days a week, cut abdominal pain by 50 percent and reduced stool frequency by 40 percent in Crohn’s disease patients with overweight or obesity. Those in the fasting group also showed lower levels of systemic inflammation and lost a clinically significant amount of body fat.

“People in the fasting group had a greater improvement in their GI [gastrointestinal] symptoms related to Crohn’s disease, so they deepened their clinical remission status,” Maitreyi Raman, a gastroenterologist, associate professor of medicine at the University of Calgary, and the study’s senior author, told The Epoch Times.

The trial recruited 35 people with Crohn’s disease in remission and randomly assigned them to either a fasting or a control group.

The fasting group was encouraged to finish their last meal earlier in the evening, creating a prolonged overnight fast. The control group continued their usual eating pattern. Researchers measured participants’ body mass index and collected stool and blood samples.

Those in the fasting group lost more weight, with an average 1-point reduction in body mass index—considered clinically significant weight loss—as well as significant reductions in visceral fat, the fat deep in the abdomen that surrounds internal organs.

Symptom severity, measured by the Harvey-Bradshaw Index, a symptom-based questionnaire that assesses stool frequency, abdominal pain, and overall well-being, improved substantially.

It’s Not About Eating Less

Interestingly, the fasting and control groups ate similar amounts of calories and macronutrients throughout the trial.

Instead, researchers observed reductions in key inflammatory molecules released by fat tissue—including leptin, plasminogen activator inhibitor-1, and adipsin. These compounds, known as adipokines, can influence immune responses and inflammation.

“So we conclude that the benefits of the weight loss are not entirely related to energy restriction or energy reduction, but more related to circadian rhythms and the timing of when people were eating,” Raman said.

Fasting may improve metabolic health by making the body more responsive to insulin, improving metabolic flexibility—the ability to switch efficiently between burning glucose and fat—and modulating immune activity, Matthew Breit, a postdoctoral fellow and registered dietitian at the University of Colorado Anschutz Medical Campus, who wasn’t involved in the study, told The Epoch Times.

However, because energy intake was assessed via self-report, some benefits may still be partly driven by unmeasured changes in calorie intake.

The Gut’s Internal Clock

The fasting group also showed favorable shifts in the gut microbiome, including an enrichment of short-chain fatty acid–producing bacteria. These bacteria are often depleted in inflammatory bowel disease (IBD) and metabolic disorders and may help support gut barrier function and immune regulation.

Bacteria associated with IBD flares and gut inflammation—Bacteroides ovatus and Escherichia/Shigella species—were less abundant among participants with greater weight loss.

Many metabolic and immune processes in the gut operate on a circadian rhythm, and prolonged eating windows may disrupt that alignment, Breit said.

“Fasting may help re-synchronize these peripheral clocks,” he said. Because eating is a major cue for the body’s peripheral clocks—self-sustaining circadian timers in just about every organ and tissue outside the brain, where the master clock is—restricting meals to a consistent daytime window creates a more predictable rhythm, helping restore coordination between gut microbes, immune cells, and metabolic processes.

Why Visceral Fat Is Critical in Crohn’s

The study adds to a growing body of evidence suggesting that excess body fat, especially visceral fat, can complicate Crohn’s disease and make it harder to manage.

Higher levels of visceral fat are linked to more frequent hospitalizations, readmissions, and surgeries, as well as poorer responses to biologic therapies.

Weight management—including fasting—combined with usual medications could “lead to a lasting durable remission response,” Raman said.

Intermittent fasting may also benefit people with normal weight, she added. “People with normal weight can still have visceral fat.”

For a disease with no known cure and where long-term disease control can be difficult, the findings offer hope that meaningful improvements may come from relatively simple changes—such as giving the gut a longer overnight break.