The worldwide increase in early-onset metabolic disorders and digestive system cancers has elicited serious concern about lifestyle and diet as contributors to chronic disease risk. Disruption of circadian rhythms, particularly through nocturnal eating, is implicated in the development of various malignancies. This narrative review explored the emerging interplay between nocturnal eating, gut microbiota disruption, and early-onset cancer risk. Literature was sourced from PubMed, Scopus, Google Scholar, and Elsevier databases, emphasizing mechanistic studies and key findings in chrononutrition, microbiome research, and oncology. Nocturnal eating desynchronizes central and peripheral clocks, alters clock-gene expression, and provokes gut dysbiosis and inflammatory signaling that promote tumorigenic pathways. In contrast, daytime-aligned time-restricted eating (TRE) has shown potential to restore circadian synchrony, enhance metabolic resilience, and improve gut health even in the absence of caloric restriction. While TRE's role in cancer prevention remains hypothetical, its circadian benefits warrant further investigation. Overall, meal timing represents a modifiable factor influencing metabolic health and possibly early carcinogenesis. Aligning eating behavior with intrinsic circadian rhythms may help mitigate cancer risk and improve long-term well-being.
