“Better three hours too soon than a minute too late.”
— William Shakespeare (The Merry Wives of Windsor, Act 2, Scene 2)
Previously, in this column, I have discussed the concept of chrononutrition. Such a model underlies the complexity of the food-health relationship. We often focus strictly on what we eat, often limited to a parsed description of individual nutrients, as if we were an unmoving boat at anchor in the harbor, which is a strange position to take given that time plays such an important and central role in our lives. We readily acknowledge the importance of circadian, diurnal, and even circannual rhythms in the study of health and the application of diagnostic and therapeutic medical interventions. Increasingly, time, or chrononutrition, is being recognized as an important piece of information and an important variable in determining our individual health and wellness or disability and disease.
Glucose tolerance, the hallmark of type II diabetes, is well known to exhibit diurnal variation. Increased risk of developing type II diabetes has been consistently linked to late-night eating, higher BMI, increased body fat, and ultra-processed food consumption. This week’s study sought to look at the effects of late-night eating independent of body weight, fat mass, daily energy intake, or diet composition in adults with overweight and obesity and diet or metformin-controlled prediabetes or type II diabetes (T2D).
- The study examined 26 adults aged 50-75 who were overweight or obese, had diet or metformin -controlled prediabetes, or T2D, and a hemoglobin A1c of 5.7-7.5%.
- The group consisted of 17 women and 9 men.
- The study data was collected over a two-week period.
- Diet composition and timing were assessed using dietary recalls.
- Late eaters consist of those consuming 45% or more of daily calories after 5 PM.
- Early eaters were all the others.
- The two groups consumed equal amounts of calories (but consumed them at different times).
- Late eaters ate more carbohydrates and fats during the evening.
- Late eaters exhibited significantly worse glucose tolerance independent of body weight, fat mass, energy intake, or diet composition.
The Caveat:
This study contributes to a growing body of evidence indicating that the when of what we eat, independent of what we actually eat, is an important variable and piece of information in our food-health equation. The findings are in line with previous studies, such as a prospective observational epidemiologic study of over 2500 women that showed that simply eating after 9 PM increased the risk of developing type II diabetes by 1.5 times.[1]
The previous conventional wisdom was that late eating led to weight gain, and subsequent weight gain led to an increased risk of type II diabetes, in a linear A+ B equals C type of effect. What this study highlighted was simply the “timestamp” of the meal itself affected the risk of T2D in a way that is independent of the caloric content or the individual’s underlying body weight and body fat. Our current approach to food often focuses – to excruciating detail – on individual micronutrient composition, macronutrient categorization, and caloric content to the exclusion of all else. According to the lead author, Dr. Díaz-Rizzolo, “With this study, a new factor in cardiometabolic health is beginning to become increasingly important: when we eat.”
[1] (Faerch, 2019)
The Study:
Additional resources:
