Abstract
BACKGROUND: The global prevalence of obesity and metabolic disorders has reached critical levels, with over 1 billion individuals affected as of 2024. Traditional dietary strategies focusing on caloric restriction and macronutrient composition have yielded modest success. Emerging evidence suggests that when food is consumed, termed circadian nutrition, is an influential, yet underutilized factor in metabolic regulation. OBJECTIVE: This narrative review examines how aligning meal timing with endogenous circadian rhythms modulates energy balance, hormonal regulation, and adiposity. It integrates recent mechanistic insights and synthesizes evidence from both animal and human studies to explore the metabolic impact of circadian-aligned eating patterns. METHODS: A comprehensive review of peer-reviewed literature (2013-2025) was conducted using PubMed, Scopus, and ScienceDirect, focusing on studies of circadian rhythms, nutrient timing, time-restricted eating (TRE), and metabolic outcomes. English-language human trials and mechanistic animal studies, relevant systematic reviews/meta-analyses were consulted. Key findings were synthesized across clinical trials, observational cohorts, and experimental models. KEY FINDINGS: Meal timing exerts significant effects on glucose metabolism, lipid regulation, and inflammatory pathways. Importantly, emerging evidence from animal models with isocaloric controls suggests that these benefits are not solely due to reduced caloric intake but also reflect independent effects of aligning food intake with circadian rhythms. Consuming a higher proportion of energy earlier in the day, with potentially more favorable distributions of carbohydrates, protein, and micronutrients, avoiding late-night eating, and practicing time-restricted feeding have been associated with improvements in insulin sensitivity, weight regulation, and cardiometabolic health. Disruptions in circadian rhythms, as seen in shift workers or individuals with irregular eating schedules, contribute to metabolic dysregulation and obesity risk. CONCLUSION: Circadian-aligned eating may offer a feasible adjunct to standard dietary strategies, but effect sizes remain uncertain given that much of the literature comprises small, short-term, heterogeneous trials. Larger, longer, and more diverse RCTs and pragmatic studies are needed to establish durability, clinical significance, and population-specific guidance.