Breakfast study challenges previous beliefs on metabolism and time-sensitive eating

16 Sep 2022 --- Research published in Cell Metabolism funded by the Medical Research Council found that the same amount of calories were burned independent of at what time of day they were consumed. Eating a large breakfast was beneficial for appetite control, which plays a central role in weight management, although it did not affect metabolism.

Although there was no sign of weight gain when eating a more significant portion late during the day, previous studies have shown a higher likelihood of gaining weight if dining in the evening, a belief now challenged by the new findings.

“Perhaps you have heard of the meme ‘breakfast like a king and dine like a pauper,’ and that is partly what we did. We fed the volunteers with a big breakfast and a small evening meal, or a small breakfast and a large evening meal,” says Alexandra Johnstone, professor at the University of Aberdeen’s Rowett Institute, UK.

Chrono-nutritionThe scientists found that appetite was more controlled when eating a larger meal at the start of the day.
However, the research also found that those who consumed their most calories at the start of the day felt less hungry throughout the day compared to those who ate most of their calories during the evening. Appetite control is known to play a crucial role in weight loss.

In addition to controlling appetite, the findings suggest that there is no difference between the body’s ability to burn calories depending on the time of eating, as previously believed. 

“This study challenges the previous belief that eating at different times of the day leads to differential energy expenditure. The research shows that under conditions of weight loss, there is no optimum time to eat to manage weight and that change in body weight is determined by energy balance,” says Jonathan Johnston, professor of Chronobiology and Integrative Physiology at the University of Surrey, UK.

Calories during day and night
Previously, industry members have spoken with NutritionInsight on the benefits of chrono-nutrition – consuming the biggest meal at the start of the day and gradually decreasing until evening – explaining that one calorie in the morning counts as 0.9, compared to one calorie in the evening which translates to 1.1.

Additionally, researchers in Japan have stressed the importance of a high protein breakfast for skeletal and muscle health, as the average protein intake during breakfast is 15 g and dinner is 28 g, arguing that breakfasts should include higher protein levels. The study is also built on the concept of chrono-nutrition.

“Our study disproves earlier studies that infer time-of-day calorie intake may influence energy balance through metabolic adaptation and instead implies that changes in appetite may be involved in improving weight loss,” the new study notes.

The study participants were overweight or obese, leading the scientists to argue that further research is needed to support the findings across a larger population. Furthermore, potential bias must be considered as participants may have consumed unrecorded meals.

Edited by Beatrice Wihlander