The modern lifestyle, characterized by uncontrolled eating, fast rhythm and lack of regular periods of metabolic rest, has significantly influenced the increase in chronic morbidity and the destabilization of the intestinal microbiota. Together with environmental pollution and constant stress, these factors have contributed to the deterioration of the population's health, prompting the search for natural and effective alternatives for rehabilitation. Fasting, known for centuries as a spiritual and physiological practice, has gained increasing interest in recent decades as a possible strategy for metabolic regeneration, increasing insulin sensitivity, stimulating autophagy and significantly improving the intestinal microbiota. Numerous studies at the global level in animal and human models clearly demonstrate the potential of fasting for cell regeneration, reducing inflammation and increasing the body's protective capacities. The aim of this study is to investigate the impact of fasting on the remodeling of thegut microbiota and the improvement of metabolic and mental functions. Special attention is givento the distinction between the microbiota inherited at birth and the one gradually shaped throughout life by nutrition and lifestyle. The analysis is structured around a theoretical framework developed step bystep, unraveling the biological mechanisms triggered during fasting and their effects onthegut microbiota. A multidisciplinary perspective is adopted, incorporating insights on autophagy, stem cells, ketone body production, and refeeding phases in relation to the intestinal flora. Complementary laboratory data are included, primarily from the scientific literature, alongsideselected original food analyses. These are not only for their nutritional value alone, but tobetterunderstand how specific foods promote or hinder the growth of beneficial gut microbe. Fasting, through temporary suspension of food intake, activatesmetabolic pathways that support the regeneration of the gut microbiota and enhance insulinsensitivity. Reduced oxidative stress, increased mental clarity, and a more stable microbial composition were observed. Fasting represents a natural and controlled mechanism for rebalancing the body–microbiota relationship, offering significant benefits for metabolism, cognition, and long-termwell-being.When applied carefully and adapted to individual needs, it can serve as a powerful preventive and supportive health strategy.