Late‐Night Eating‐Induced Physiological Dysregulation and Circadian Misalignment Are Accompanied by Microbial Dysbiosis

Scope Irregular eating habits, such as late‐night eating, will cause increased risk of obesity and other metabolic diseases. The aim of this study is to elucidate the impacts of late‐night eating on physiological function and gut microbiota. Methods and results Male Wistar rats under 16 h/8 h‐light/dark cycle are divided into four groups with specific dietary habits, which mimicked breakfast, lunch, dinner, and late‐night eating. Late‐night eating, including skipping dinner for a night eating (BLN) and skipping breakfast and having a night eating (LDN), causes an increase of body weight, which is associated with decreased physical activity. Additionally, late‐night eating results in hepatic lipid accumulation and systemic inflammation in peripheral tissues, compared to those of free feeding (FF) or breakfast, lunch, and dinner (BLD) groups. The phases of key clock genes are similar in FF, BLD, and BLN groups, while LDN feeding causes an overall 4 h phase delay in peripheral tissues. Moreover, late‐night eating, especially LDN feeding, results in a significant alternation in the compositions and functions of gut microbiota, which further contributes to the development of metabolic disorder. Conclusion Late‐night eating causes physiological dysregulation and misalignment of circadian rhythm, together with microbial dysbiosis. Late‐night eating results in more body weight gain, which is associated with decreased physical activity, hepatic lipid accumulation, and systemic inflammation in peripheral tissues. The impact of late‐night eating on these physiological functions might be partly induced by the misalignment of circadian clock. Late‐night eating also results in impaired gut barrier function and microbial dysbiosis, which further contributes to the development of metabolic disorder.