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Late Eating Linked to Impaired Glucose Metabolism
Last reviewed: 15.07.2025
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Our metabolic processes are influenced by the time of day, and many of them are more active in the morning than in the evening. Although research shows that eating late at night is associated with an increased risk of obesity and cardiovascular disease, little is known about how meal timing affects glucose metabolism and the extent to which this is determined genetically.
Professor Olga Ramikh from Germany’s Leibniz Institute for Human Nutrition (DIfE) and her team recently explored this question using data from the 2009–2010 twin cohort. Their paper was published in the journal eBioMedicine.
The circadian system and nutrition
The circadian system is a hierarchically organized 24-hour time control system in the body that regulates behavior and metabolism via a central clock in the brain and peripheral clocks in organs such as the liver and pancreas. As a result, our metabolic processes differ depending on the time of mealtime, leading to diurnal variations in glucose metabolism and postprandial hormone release.
Food itself acts as an important timer, synchronizing our internal clocks. Disruption of meal timings with the natural light-dark rhythm, such as when working at night, can lead to disruption of the biological clock and negative metabolic changes.
Does eating late at night make us sick?
Previous studies have shown that late dinners are associated with an increased risk of obesity and cardiovascular disease.
However, little is known about how meal timing interacts with an individual’s circadian rhythm and thus influences glucose metabolism and diabetes risk. It also remains unclear what mechanisms determine individual eating behavior, as it depends on a combination of cultural, personal, physiological, and genetic factors.
Circadian timing of food intake
At what point in the day a person eats relative to their biological rhythm is measured as the interval between mealtime and midsleep. Midsleep is defined as the point exactly halfway between the time a person falls asleep and wakes up. It is a measure of chronotype—in other words, whether a person is a morning person or a night owl.
NUGAT Twin Study
The NUGAT (Nutrigenomics Analysis in Twins) study, initiated and designed by Professor Andreas F. H. Pfeiffer, was conducted in 2009–2010 at the DIfE. Twin pairs (identical and fraternal) were recruited through a twin registry (HealthTwiSt, Berlin, Germany) or through public advertisements.
The study involved 92 people (46 pairs of twins) who underwent two dietary interventions (not relevant to the results presented here).
Participants underwent detailed metabolic phenotyping, including physical examination, medical history, anthropometric measurements, and glucose tolerance test. Individual chronotype was determined using a questionnaire.
In addition, all 92 participants kept handwritten food diaries in which they recorded the start and end times of each meal, as well as the amount and type of food eaten, for five consecutive days (three weekdays and two weekends) to reflect the twins' eating habits.