Meal timing affects glucose tolerance and health

Although people have always argued that a light and early dinner is better, a study conducted at the Universitat Oberta de Catalunya (UOC) and Columbia University provided scientific support for this claim. According to a study published open access by the group’s journal Nature, consuming more than 45% of daily calories after 5 p.m. is associated with an increase in glucose levels, which has harmful health consequences regardless of body weight and body fat content.

The study was conducted at the Irving Medical Center at Columbia University in New York and was led by Dr. Diana Díaz Rizzolo, a PhD student and member of the UOC Faculty of Health Sciences.

Maintaining high glucose levels for long periods of time can have consequences, including an increased risk of progression to type 2 diabetes, an increased risk of cardiovascular disease due to the damage that high glucose levels do to the blood vessels, and an increased risk of chronic inflammationwhich deepens damage to the circulatory system and metabolism.”

Dr. AS Diana Diaz Rizzolo, PhD student and member of the Faculty of Health Sciences at UOC

Experts previously believed that the main consequence of eating dinner late in the day was weight gain. This was linked to the fact that people tend to make poorer food choices at night, such as eating more ultra-processed foods, because the hormones that regulate hunger and satiety are altered when people don’t eat during the day.

The significance of the study is that it shows that the time of day at which meals are eaten can itself have a negative impact on glucose metabolism, regardless of the amount of calories consumed during the day and a person’s body weight and body fat.

“The time of day at which meals are eaten may itself have a negative impact on glucose metabolism.”

Late eaters vs. early eaters

The study involved 26 participants aged 50 to 70 who were overweight or obese and had prediabetes or type 2 diabetes. They compared the participants’ glucose tolerance levels and divided them into two groups: early eaters, who consumed most of their daily calories before the evening, and late eaters who consumed 45% or more of their calories after 5 p.m. they consumed the same amount of calories and the same products during the day, but at different times. Participants used a mobile app to record their meals in real time.

The main finding of the study is that late eaters had worse glucose tolerance, regardless of their body weight and diet composition. It also turned out that in the evening they consumed larger amounts of carbohydrates and fats.

Díaz Rizzolo, an expert on obesity, diabetes and aging, explained that “the body’s ability to metabolize glucose at night is reduced because insulin secretion decreases and the sensitivity of our cells to this hormone decreases due to the circadian rhythm, set by the central clock in our brain, coordinated with the hours of day and night.”

The importance of eating at the right time

The study therefore contains an important finding about its health implications and the time of day at which people eat. “Until now, personal decisions about nutrition have been based on two main questions: how much we eat and what foods we choose. Thanks to this study, a new factor influencing cardiometabolic health is beginning to become increasingly important: when we eat,” he says. Diaz Rizzolo.

With the results of the study in mind and considering them with due caution as further research will be needed to better understand the topic, the researcher recommends that food should be consumed primarily during daylight hours and that “the highest levels of calories throughout the day should be at breakfast and lunch, and not for afternoon tea and dinner.” Díaz Rizzolo also recommends avoiding ultra-processed products, fast food and foods high in carbohydrates, especially at night.