When late-night snacking meets high stress levels, your digestive system may pay the price, according to new research presented at a major gastroenterology conference.

Scientists found that consuming more than a quarter of daily calories after 9 p.m. while under stress was linked to as much as 2.5 times higher odds of experiencing digestive issues such as constipation or diarrhea.

The findings come from preliminary, observational data and have not yet been peer-reviewed or published in a scientific journal. The results were unveiled at Digestive Disease Week, a prominent annual meeting for specialists in gastroenterology, hepatology, and related fields.

Lead author Dr. Harika Dadigiri, a resident physician at New York Medical College at Saint Mary's General Hospital and Saint Clare's Denville Hospital, said she began exploring the issue after noticing a lack of research on late-night eating beyond its known ties to sleep and metabolic conditions.

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Her team examined data from 11,149 participants who were part of the 2005 to 2010 National Health and Nutrition Examination Survey, along with over 4,100 individuals from the 2013 to 2017 American Gut Project, now called the Microsetta Initiative.

Dr. Geoffrey Preidis, an associate professor at Baylor College of Medicine and Texas Children's Hospital who was not involved in the study, said the work is important because "stress and excess late-night eating often go hand in hand."

The researchers used a composite allostatic load score—a measure that includes eight biological markers like blood pressure, cholesterol, and body mass index—to identify participants under chronic physiological stress.

Interestingly, late-night eating alone did not appear to disrupt gut health. Dadigiri reported that only when combined with high stress did the pattern appear to affect gastrointestinal function.

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In addition, an analysis of gut microbiome data showed that participants who both ate late and reported high stress had significantly lower bacterial diversity in their intestines.

Preidis explained that the gut microbiota contains a wide array of bacteria, viruses, and fungi, and greater diversity often helps the body recover from illnesses and other stress-related changes.

Different microbes play key roles in nutrient absorption, immune regulation, and communication with the brain that influences sleep and mood, he noted.

However, since the data capture only a single point in time, it remains unclear whether stress and late-night eating cause changes in gut bacteria or whether altered gut environments worsen bowel habits.

Dr. William Chey, president of the American College of Gastroenterology, said that dietary differences between early and late eaters could also contribute, especially if late-night meals consist largely of ultraprocessed foods.

Chey emphasized that the study should be considered hypothesis-generating rather than conclusive, urging more research on whether meal timing could potentially modify risks for constipation or diarrhea.

If future studies confirm a causal link, Preidis added, it may be because both the body and gut microbiome follow circadian rhythms that can be disrupted when eating patterns shift.

Such disruptions might alter gut motility—the movement of food through the intestines—and interfere with hormones and immune responses tied to digestion.

Dadigiri cited a 2024 study suggesting that restricting eating to between 9 a.m. and 5 p.m. reduced inflammation related to gut imbalance, while elevated cortisol levels alone may trigger similar changes.

Although the new abstract does not offer specific health advice, independent experts provided some general guidance on timing and food choices before bed.

Dr. Kyle Staller, director of the Gastrointestinal Motility Laboratory at Massachusetts General Hospital, said avoiding meals within three to four hours of bedtime allows the stomach to empty and supports restorative rest.

He and Preidis both recommended smaller, lighter nighttime snacks when necessary, focusing on foods such as fruits, vegetables, complex carbohydrates, and lean proteins instead of heavy or greasy meals.

The early findings highlight how stress and timing may together contribute to disruption in gut health, prompting new questions about how eating habits influence overall well-being.