Late eating is associated with impaired glucose metabolism, suggests study

Our metabolic processes differ depending on the time of day and many of them are more active in the morning than in the evening. Although studies show that eating late in the day is associated with an increased risk of obesity and cardiovascular diseases, little is known about how the time when we eat affects glucose metabolism and to what extent this is genetically defined. Prof. Olga Ramich from the German Institute of Human Nutrition Potsdam-Rehbrücke (DIfE) and her team recently investigated this in a twin cohort. The article was published in the journal eBioMedicine.

The circadian system is a hierarchically structured 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 or pancreas. As a result, our metabolic processes differ depending on the time when we eat, which leads to diurnal fluctuations in glucose metabolism and the release of hormones after a meal. Food intake itself acts as an important timer that synchronizes our internal clocks. Decoupling meal times from the natural light-dark rhythm, e.g. when working at night, can lead to an internal clock disorder and negative metabolic changes.

Does late eating make you ill?

Previous studies have shown that eating late at night is associated with an increased risk of obesity and cardiovascular diseases.

However, little is known about how exactly the timing of food intake interacts with the individual circadian rhythm and thus influences glucose metabolism and the risk of diabetes. It is also unclear which mechanisms determine one’s individual eating behavior, as it depends on the interaction of cultural, personal, physiological and genetic factors.

Circadian Timing of Eating

When someone eats during the course of a day in relation to the individual biological daily rhythm is measured as the interval between mealtime and the midpoint of sleep. The midpoint of sleep describes the time that lies exactly in the middle between falling asleep and waking up. It is a measure of the chronotype – in other words, whether someone is an early riser or a night owl.

NUtriGenomics Analysis in Twins (NUGAT) Study

The NUGAT study, initiated and designed by Prof. Andreas F. H. Pfeiffer, was conducted from 2009 to 2010 at the German Institute of Human Nutrition Potsdam-Rehbrücke (DIfE). The identical and fraternal twin pairs were recruited either from a twin register (HealthTwiSt, Berlin, Germany) or via public advertisements. The 92 participants (46 pairs of twins) underwent two nutritional interventions, which were not relevant to the study results shown here though.

The participants underwent detailed metabolic phenotyping, which included a physical examination, medical history, anthropometric measurements and a glucose tolerance test. The individual chronotype was determined by means of a questionnaire. In addition, all 92 test subjects filled out handwritten food logs in which they noted the start and end of each meal as well as the amount and type of food consumed on five consecutive days. This included three working days and two days off to reflect the eating habits of the twin pairs.

Reference:

Vahlhaus, Janna et al., Later eating timing in relation to an individual internal clock is associated with lower insulin sensitivity and affected by genetic factors, EBioMedicine, DOI: 10.1016/j.ebiom.2025.105737.