Late-Night Eating and Digestive Health: New Insights

ATLANTA — If you’re feeling stressed, eating late at night might not be the best idea for your digestion.

In a preliminary study, researchers found that participants consuming over 25% of their daily calories after 9 p.m. while experiencing stress were up to 2.5 times more likely to have irregular bowel habits, like constipation or diarrhea.

This research, an abstract presented at Digestive Disease Week in May, hasn’t been peer-reviewed yet. It merely reflects observations taken at a single point in time, so it doesn’t establish a cause-and-effect link between stress, nighttime dining, and gut health.

Lead author Dr. Harika Dadigiri, who often finds herself eating late, mentioned her curiosity prompted her to pursue this study. While there’s plenty of existing research on late-night eating related to sleep, diabetes, obesity, and acid reflux, not much addresses its impact on bowel function.

The analysis involved health data from over 11,000 participants from the 2005 to 2010 cohort of the National Health and Nutrition Examination Survey, along with more than 4,100 individuals from the American Gut Project, which now operates as the Microsetta Initiative. The later data lacked some details the researchers wanted, explained Dadigiri, who works as a resident physician in New Jersey.

“Previous studies haven’t really looked into how meal timing interacts with stress on bowel health,” Dr. Geoffrey Preidis, a pediatrics associate professor at Baylor College of Medicine, stated in an email. “This could be significant because stress and nighttime eating are often linked.”

Meal Timing’s Role in Gut Health

The study classified chronic physiological stress using a composite allostatic load score, which reflects various biomarkers such as blood pressure and body mass index.

Interestingly, eating late alone didn’t seem to hurt gut health. It was the combination with stress that raised concerns, Dadigiri pointed out in her presentation.

Their analysis of the American Gut Project indicated that people who both ate at night and faced high stress levels had noticeably less diverse gut bacteria. “Our gut microbiota includes a range of organisms—bacteria, viruses, and fungi—that reside in our intestines,” Preidis explained. A diverse microbiome tends to recover more effectively from disturbances like illnesses or stresses.

Different microbes support various health functions, such as aiding nutrient absorption and regulating our mood, Prreidis noted. Still, it remains ambiguous whether the microbiome issues led to abnormal bowel behavior or the other way around, he added.

There are also notable factors missing from the data, according to Dr. William Chey, the president of the American College of Gastroenterology. For example, the types of food eaten at different times could vary significantly.

If late-night meals typically include ultraprocessed foods, these could contribute to bowel issues like constipation, Chey pointed out. Plus, the study lacked detailed information about any existing medical conditions or medications.

Chey emphasized that the findings are more of a basis for further investigation rather than conclusive evidence. If later studies confirm a causal relationship, Preidis offered several potential explanations. “Both our bodies and gut microbiomes follow natural rhythms that can be disturbed by changes in when and what we eat. Such disruptions might impact hormones, gut signaling, and the movement of food through the digestive system.”

Movements through the digestive tract, referred to as motility, is crucial for proper digestion.

A separate study from 2024 indicated that restricting eating to a window between 9 a.m. and 5 p.m. could help reduce gut inflammation, which might lead to gut imbalances. High cortisol levels, a stress hormone, can also contribute to these imbalances.

Recommended Habits for Evening Meals

While the abstract isn’t sufficient for giving specific diet recommendations, healthcare experts have some general advice to promote digestive health.

It’s usually best to avoid eating three to four hours before sleeping, as this allows the stomach to empty adequately. Otherwise, your body might struggle to balance digestion with other essential processes during rest, according to Dr. Kyle Staller, a director at Massachusetts General Hospital.

Additionally, limiting late-night meals can help prevent acid reflux. If you need a nighttime snack, experts recommend steering clear of heavy, greasy foods and sticking to smaller portions. Foods like fruits, vegetables, complex carbohydrates, and lean proteins usually digest more swiftly.