Love late-night ice cream? It might be hurting your digestive health, shows study

“It’s not just what you eat, but when you eat it,” said Dr. Harika Dadigiri, resident physician at New York Medical College at Saint Mary’s and Saint Clare’s Hospital, and the study’s lead author. “And when we’re already under stress, that timing may deliver a ‘double hit’ to gut health.”

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Researchers analysed data from more than 11,000 participants in the National Health and Nutrition Examination Survey to examine the connection between chronic stress, late-night eating, and bowel dysfunction.

The study found that individuals with a high allostatic load score — a measure of cumulative physiological stress reflected in factors such as body mass index (BMI), cholesterol levels, and blood pressure — who also consumed more than 25% of their daily calories after 9 p.m. were 1.7 times more likely to experience constipation and diarrhea compared to those with lower stress levels who did not eat late at night.

Similarly, data from more than 4,000 participants in the American Gut Project showed that people with both high stress levels and late-night eating habits were 2.5 times more likely to report bowel problems.

These individuals also had significantly lower gut microbiome diversity, suggesting that meal timing may amplify the impact of stress on the microbiome through the gut-brain axis — the two-way communication system involving nerves, hormones, and gut bacteria.

The study was observational, meaning it highlights associations rather than proving direct cause and effect. Researchers say further studies are needed to better understand how stress, eating patterns, and gut health are interconnected.

Still, the findings support the growing field of chrononutrition, which examines how the body’s circadian rhythm influences the way it processes food.

Dr. Dadigiri acknowledged that many people turn to late-night snacks after long, stressful days — something she relates to as a medical resident herself.

“I’m not the ice cream police,” she said. “Everyone should eat their ice cream — maybe preferably earlier in the day. Small, consistent habits, like maintaining a structured meal routine, may help promote more regular eating patterns and support digestive function over time.”