A randomized clinical trial led by researchers at the University of Calgary shows that time-restricted eating, a form of intermittent fasting, reduced Crohn’s disease activity by 40% and abdominal discomfort by 50% over 12 weeks in adults with Crohn’s disease and overweight or obesity. Published in the journal Gastroenterology, the study showed that participants who limited eating to an eight-hour daily window also showed reductions in visceral fat and blood markers linked to inflammation and immune regulation, without cutting their daily caloric intake.
“This study shows that while weight loss is an important outcome in people with overweight and Crohn’s disease, time-restricted feeding offers additional benefits beyond just the scale,” said senior study author Maitreyi Raman, MD, an associate professor of medicine at the University of Calgary. “We saw meaningful improvements in disease symptoms, reduced abdominal discomfort, favorable shifts in metabolism and inflammation, and promising changes in gut bacteria—all suggesting that intermittent fasting may help patients maintain lasting remission from Crohn’s disease.”
Overweight and obesity (OO) affect roughly 40% of people with Crohn’s disease. Excess visceral adipose tissue is associated with metabolic changes, systemic inflammation, poorer quality of life, reduced response to biologic therapies, and increased surgical risk. In the general population, intermittent fasting has been linked to reductions in visceral fat, insulin resistance, and circulating cytokines independent of calorie restriction. “Despite the high prevalence of OO in IBD, lifestyle interventions specifically targeting adiposity and metabolic dysfunction remain underexplored,” the researchers wrote, noting that no controlled trials had evaluated time-restricted feeding in inflammatory bowel disease (IBD).
To address this gap, the Calgary team conducted a 12-week randomized controlled trial in 35 adults with Crohn’s disease in clinical remission who were living with OO. Twenty of the participants were assigned to the time-restricted feeding group with another 15 assigned to the control that continued their usual eating patterns. Those in the intermittent fasting group fasted for 16 consecutive hours per day, six days per week, while consuming their usual diet within an eight-hour window. People in the control group ate their meals without any restrictions.
Researchers measured disease activity, body composition, and markers of inflammation and immune-metabolic health at the beginning of the study and again at week 12. Data points in the trial included body mass index (BMI), analysis of stool samples for fecal calprotectin and microbiota analyses, and serum samples for adipokines and cytokines. Energy intake and diet quality were also assessed to determine whether changes were related to calorie reduction or food choices.
Over the study period, the BMI of participants in the time-restricted feeding group decreased compared with an increase among the controls, despite similar energy intake and diet quality between. Clinical disease activity, assessed using the Harvey–Bradshaw Index, improved in the intervention group, with a 40% decrease in stool frequency and a 50% reduction in abdominal discomfort. These changes were not observed in controls.
Intermittent fasting was also associated with reductions in serum leptin, plasminogen activator inhibitor-1, and adipsin, hormones linked to adiposity, inflammation, and immune regulation. In a subset of participants with DEXA scans, visceral adipose tissue decreased in the time-restricted feeding group but increased in controls. “Together, these hormonal and body composition changes strengthen evidence that [time-restricted fasting] improves adipose tissue distribution and metabolic health,” the researchers wrote.
Further analyses of the study data showed that immune and microbial changes might also accompany the observed clinical and metabolic effects. Among participants who had greater reductions in BMI, changes occurred in both anti-inflammatory and pro-inflammatory cytokines, which the researchers think may reflect “an evolving process of immune recalibration.”
The research was informed by prior studies that have shown intermittent fasting can influence immunometabolic pathways by modulating circadian rhythms in the gut and coordinating immune and microbial activity. The observed reduction in leptin, a hormone involved in energy balance and immune signaling, gives credence to the notion that modifying adiposity may mitigate systemic inflammation in Crohn’s disease.
The findings have the potential to influence the care of OO patients with Crohn’s disease to include time-restricted feeding alongside other medications. The authors cautioned OO and Crohn’s patients not to make any dietary changes without first consulting their healthcare provider. Nonetheless, the research team is hopeful their findings can be the first evidence on a pathway to providing additional relief to a subset of patients.
“People with Crohn’s disease often look for practical tools to support their health alongside medication,” said lead author Natasha Haskey, PhD, RD, a research associate at the University of British Columbia. “Our research suggests time-restricted eating may be a sustainable option grounded in biology, offering patients more ways to manage their own wellness.”
Based on the success of this pilot study, the investigators are now planning multi-center trials with longer follow-up and comparator groups to determine long-term safety, clarify weight-independent mechanisms, and assess whether time-restricted feeding can help maintain remission across broader IBD populations.
