While some people are already full of steam in the morning, others don’t get hungry until later in the day. So what role does the time of day play when eating? Several studies are examining what it means for the body when you eat.

“Eat in the morning like an emperor, at noon like a nobleman and at night like a pauper.” Many people may still have these words in their ears when it comes to the three main meals. But what role does time play when eating?

For a long time it was questionable whether the time of day had any influence at all. “It used to be assumed that a calorie is a calorie and that it makes no difference when it is consumed,” says Olga Ramich, head of the Molecular Nutritional Medicine research group at the German Institute for Human Nutrition Potsdam-Rehbrücke (DIfE). And indeed, there are studies that confirm this at first glance: just recently, a team from the Scottish University of Aberdeen reported that, at least in terms of energy metabolism, it makes no difference whether you consume the majority of your daily calories in the morning or in the evening.

However, the overweight subjects noted a benefit of a large breakfast, co-author Alexandra Johnstone said in a statement: “Participants reported that on the days they ate a larger breakfast, they had better appetite control and increased appetite feeling full for the rest of the day.”

This observed feeling of satiety is of particular interest to Olga Ramich: “Although this does not result in direct regulation of the metabolism through the distribution of calories over time, it does have a positive effect on behavior.” In addition, other studies have shown that the time of day influences the metabolic response triggered by the meal.

“For example, my research group conducted studies in which we compared the effects of the same meal in the morning and in the afternoon,” says Ramich. “We found that blood sugar rises significantly more after a late meal than in the morning.” The body is also better able to metabolize carbohydrates in the morning.

This observation fits with a study by the University of Lübeck. In this, 16 normal-weight men received a low-calorie breakfast and a high-calorie dinner in the first phase and vice versa in the second phase. As the research team observed, the rise in blood sugar and insulin levels was significantly reduced after breakfast compared to dinner. The scientists concluded that the human energy turnover is generally higher in the morning than in the evening.

Work like this is particularly interesting for the so-called chrono-nutrition. This field of research examines the connection between the biological clock and food intake, which has often been neglected in the past. But it is precisely this connection that is extremely important, says Ramich from DIfE: “Everything is time-dependent: the circadian clock determines both metabolic processes and our behavior.”

A distinction is made between two so-called chronotypes: while larks have energy in the morning and tend to go to bed earlier, owls stay awake longer and find it difficult to get going early in the day. Owls in particular would tend to skip breakfast. According to some studies, they also consume more fast food, coffee and alcohol, as Olga Ramich explains.

Part of this unhealthy behavior is believed to be due to the fact that social rhythm often works against owls’ biological rhythms. “People like that in particular should pay attention to a healthy diet, fixed meal times and breakfast,” emphasizes Ramich, referring to studies that show that skipping the morning meal increases the risk of cardiovascular disease, nutrient deficiencies, obesity and type 2 diabetes elevated. “Owls are often not hungry in the morning, but even they are recommended to get used to eating at least a little something for breakfast.”

Overall, according to nutritionist Ramich, the saying “breakfast like a king” is probably correct. Nevertheless, the total amount of calories for the day should be taken into account when having a hearty breakfast: “Of course, it’s not just important when you eat, but also what you eat and how much you eat. And that should be balanced and healthy, especially at breakfast.”

(This article was first published on Saturday, December 31, 2022.)