Influence of Fasting until Noon (Extended Postabsorptive State) on Clock Gene mRNA Expression and Regulation of Body Weight and Glucose Metabolism

Abstract

The trend of fasting until noon (omission or delayed breakfast) is increasingly prevalent in modern society. This eating pattern triggers discordance between endogenous circadian clock rhythms and the feeding/fasting cycle and is associated with an increased incidence of obesity and T2D. Although the underlying mechanism of this association is not well understood, growing evidence suggests that fasting until noon, also known as an “extended postabsorptive state”, has the potential to cause a deleterious effect on clock gene expression and to disrupt regulation of body weight, postprandial and overall glycemia, skeletal muscle protein synthesis, and appetite, and may also lead to lower energy expenditure. This manuscript overviews the clock gene-controlled glucose metabolism during the active and resting phases and the consequences of postponing until noon the transition from postabsorptive to fed state on glucose metabolism, weight control, and energy expenditure. Finally, we will discuss the metabolic advantages of shifting more energy, carbohydrates (CH), and proteins to the early hours of the day.

Timing Matters: The Interplay between Early Mealtime, Circadian Rhythms, Gene Expression, Circadian Hormones, and Metabolism—A Narrative Review

“…Research indicates that early breakfast activates the “CLOCK: BMAL1” complex, initiating gene transcription of PERs and CRYs, and subsequent physiological processes [ 2 , 79 ]. Interactions between genes such as AMPK, SIRT1, and CLOCK-BMAL1 drive tissue-specific expressions like increased insulin secretion, enhanced GLP-1 response post meals, and glucose uptake in muscles [ 80 ].…”

“…This leads to a reduction in hepatic glucose production, resulting in increased glucose utilization and decreased fat accumulation during the early hours of the day [ 14 , 83 ]. In contrast, lower levels of adiponectin in the evening bring about metabolic changes that favor insulin-mediated anabolic processes [ 2 ]. As a result, the insulin response following a meal during the evening promotes the accumulation of fat and the process of lipogenesis through the activation of fatty acid synthesis [ 14 , 82 ].…”

“…Therefore, having breakfast at an earlier time (dawn meal) aligns with the transition of the circadian clock, facilitating metabolic processes like glucose uptake, insulin sensitivity, and the production of glycogen. This synchronization of mealtime with the central clock aids in maintaining the coordination of peripheral clocks in metabolic tissues such as the liver, skeletal muscle tissue, and fat tissue [ 2 ].…”

“…The regulation of clock genes has been found to improve insulin sensitivity, the responsiveness of β-cells, the activity of GLUT-4, glucose uptake in muscles, and the secretion of post-meal incretins (GLP-1, GLP-2, and GIP); the ability to stimulate insulin release is mediated by incretins during the early hours of the active phase [ 2 ]. Various studies have supported this; consequently, various studies have reported that consuming identical meals in the evening leads to a considerably greater glycemic response compared with the morning, indicating a notable disparity in how the body processes and responds to the same meals based on the timing of consumption [ 85 , 88 , 89 , 90 , 91 , 92 , 93 , 94 ].…”

“…Numerous risk factors contribute to an increased susceptibility to metabolic diseases, necessitating a systematic approach to comprehend these factors. The timing of fasting/feeding, mealtimes, circadian rhythm, and sleep, as well as the complex interplay between these elements, may exert influence on the circadian rhythms of various organs and cells within the body, particularly when food intake occurs at inappropriate intervals relative to the body’s circadian clock [ 2 ].…”