An unhealthy diet, certain medications, poor sleep hygiene, mental health conditions like depression, and a sedentary lifestyle are all factors that can lead to weight gain. But did you know that the time at which you eat dinner can also influence the number you see on the scale? According to a new study published in the journal Nutrition & Diabetes, late eating has been linked to poor glucose tolerance, making it difficult to lose weight.
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The study involved 26 adults (17 of whom were women) between the ages of 50 and 70. Participants were overweight or obese and had been diagnosed as prediabetic or were living with type 2 diabetes. Researchers carried out the study over the course of 14 days at Columbia University Irving Medical Center in New York City. During this time, participants were classified into two groups based on dinnertime habits and had their glucose tolerance levels closely monitored in response.
To analyze the “impact of habitual late calorie intake on glucose metabolism in adults,” researchers prepared the same amount of food for both groups but spaced out their evening meal times. Those in the “Early Eaters” group ate their biggest meals before the end of the workday, while the “Later Eaters” consumed more than 45 percent of their calorie intake after 5:00 p.m.
By the time their heads hit the pillow, both groups had consumed the same amount of calories, just at different points throughout the day. Daily meals were logged in real-time using the myCircadianClock app.
After 10 hours of fasting, participants underwent a two-hour oral glucose tolerance test. Biomarkers were taken at the beginning and end, as well as at the 15-, 30-, 60-, and 90-minute mark. Additionally, researchers measured their blood pressure, weight, body mass index (BMI), waist circumference, and fat mass.
According to their findings, Later Eaters are more likely to gravitate towards foods high in fat and carbohydrates in the evening. They also consumed nearly double the amount of calories after 5 p.m compared to Early Eaters. All of this contributed to “poorer glucose tolerance,” wrote the authors.
"The body's ability to metabolize glucose is limited at night, because the secretion of insulin is reduced, and our cells' sensitivity to this hormone declines due to the circadian rhythm, which is determined by a central clock in our brain that is coordinated with the hours of daylight and night,” Diana Díaz Rizzolo, PhD, lead study author and member of the Faculty of Health Sciences at the UOC, told Medical Xpress.
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Sustaining high glucose levels can have life-threatening consequences. It can lead to “a higher risk of progressing to type 2 diabetes, an increase in cardiovascular risk due to the damage that high glucose levels do to blood vessels, and increased chronic inflammation, which aggravates cardiovascular and metabolic damage," Díaz Rizzolo added.
More research is needed to better understand the link between meal times, high glucose levels, and weight gain. But as a good rule of thumb, "the highest levels of calorie intake during the day should be at breakfast and lunch, instead of at teatime and dinner,” advised Díaz Rizzolo.
"Until now, personal decisions in nutrition have been based on two main questions: how much we eat, and what foods to choose. With this study, a new factor in cardiometabolic health is beginning to become increasingly important: when we eat," she shared.
