Intermittent fasting: a comprehensive review of cellular mechanisms, metabolic processes, and organ health

Abstract Intermittent fasting is a dietary approach characterized by alternating periods of consuming food and fasting. This review integrates findings from studies conducted between 2004 and 2024 to examine the impact of intermittent fasting on metabolic health, cellular mechanisms, and organ systems. Intermittent fasting consistently improves insulin sensitivity, lipid profiles, and body composition by promoting fat oxidation while maintaining lean mass. Mechanistically, it activates autophagy, thereby reducing oxidative stress and inflammation—critical contributors to the pathogenesis of aging and chronic diseases—as well as hormonal changes, including elevated growth hormone levels and reduced insulin levels, which contribute to maintaining metabolic homeostasis. Studies have shown that intermittent fasting has cardioprotective effects, enhances neurocognitive function, and improves gut microbiome diversity, which indicates that it offers benefits for the whole body. These findings suggest that intermittent fasting is a promising non-pharmacological intervention to improve metabolic health, decrease the risk of chronic disease, and prolong healthspan. Nonetheless, further large-scale, long-term clinical trials are warranted to standardize intermittent fasting protocols, clarify optimal fasting regimens, and evaluate sustained outcomes across different populations.