Circadian rhythms orchestrate daily fluctuations in feeding behavior, hormonal activity, and metabolic function through coordinated interactions between the central clock and peripheral oscillators. Dietary patterns, defined by both macronutrient composition and the timing of food intake, function as potent cues that reshape these rhythms. This narrative review summarizes experimental evidence describing how diet influences circadian organization and how circadian disruption alters metabolic outcomes primarily in murine models. Genetic disruption of core clock components such as CLOCK, BMAL1, CRY, or PER abolishes feeding rhythmicity and desynchronizes metabolic pathways, resulting in obesity, impaired glucose regulation, and hepatic lipid accumulation. Dietary composition also influences circadian organization, as high-fat, ketogenic, or modified-protein diets shift the phase or amplitude of peripheral clock gene rhythms and alter metabolic outputs across tissues. Feeding-time misalignment produces substantial phase shifts in hepatic and adipose oscillations and aggravates diet-induced metabolic dysfunction. In contrast, restricting food intake to consistent daily windows restores rhythmic metabolic states in the liver, adipose tissue, and intestine and improves systemic homeostasis even without reducing caloric intake. Together, these findings show that both macronutrient composition and feeding-time alignment influence the phase and synchrony of peripheral circadian rhythms and the metabolic processes governed by these rhythms. Understanding these relationships provides mechanistic insight into diet–circadian interactions and supports the development of circadian-aligned dietary strategies aimed at promoting metabolic stability.

Purpose: The present study examined the associations of Korean Food-based Index of Dietary Inflammatory Potential (FBDI) scores with the prevalence of diabetes and hemoglobin A1c (HbA1c) level of diabetes patients in Korean adults. Methods: The Korean Genome and Epidemiology Study (KoGES) Health Examinee baseline data, collected between 2004 and 2013 and followed up between 2012 and 2016, were used in our study. A total 56,391 participants including diabetes (n = 5,733) and non-diabetes (n = 50,658) were analyzed. The subjects were classified into quartiles of FBDI scores using the semi-quantitative food-frequency questionnaire developed for KoGES. The prevalence rate of diabetes under FBDI scores was assessed by Cox proportional risk models and the severity of the diabetes was analyzed by multiple regression analysis. Results: There were 775 incident cases of diabetes after a mean follow-up of 3.97 years. There was no statistically significant association between FBDI scores and incidence of diabetes.Among diabetes patients at baseline, FBDI scores were related to the risk of progression of diabetes which was represented by greater than 9% HbA1c (Q1 vs. Q4; odds ratio, 1.562 [95% confidence intervals, 1.13–2.15]; p for trend = 0.007). The stratified analysis showed a stronger association in females, irregular exercise group, and higher body mass index group. Conclusion These results suggest that a pro-inflammatory diet is not associated with the incidence of diabetes but is related to the HbA1c level of diabetes patients. Thus, further longitudinal studies with longer periods are required to determine a relationship between dietary inflammatory index and diabetes in Korea.

The Korea National Health and Nutrition Examination Survey of 2013 to 2017 reported that the average protein consumption of the Korean population is above the current recommended nutrient intake of protein proposed by the Dietary Reference Intakes for Koreans. Some health professionals and the media often advise consuming diets high in protein for promoting metabolic regulation, weight control, and muscle synthesis. However, due to lack of scientific evidence, the validity and safety of high protein consumption are yet to be fully ascertained. The present review assesses recent evidence published in 2014–2020 from human studies, focusing on adequate protein intake and protein sources for the prevention of chronic diseases, particularly metabolic disorders and sarcopenia.