Intermittent Fasting, Interoceptive Awareness, and Emotional Regulation: A Psychobiological Narrative Review

Intermittent fasting (IF) has gained increasing attention as a metabolic intervention that can improve insulin sensitivity, lipid profiles, and systemic inflammatory markers. A central feature of IF is the shift toward lipid-based energy metabolism, characterized by enhanced lipolysis, mobilization of free fatty acids, and increased production of ketone bodies. These lipid-derived substrates not only sustain energy demands during fasting states but also function as bioactive signaling molecules involved in neuroendocrine regulation and cellular stress adaptation. Despite the growing metabolic literature, the psychological and experiential dimensions of intermittent fasting (IF) remain comparatively underexplored. This narrative review advances a psychobiological framework in which IF is understood as a controlled metabolic stressor engaging lipid metabolism, stress physiology, and emotional regulation processes. Drawing on interdisciplinary evidence from neuroendocrinology, affective neuroscience, and clinical psychology, we examine how fasting-related metabolic transitions influence both peripheral and central systems. Suppose modulates stress-related pathways, including hypothalamic–pituitary–adrenal (HPA) axis activity, autonomic balance, and ketone body signaling. Within this framework, lipid-derived signals—particularly free fatty acids and ketone bodies—may influence central nervous system functioning by modulating neuroinflammatory processes, mitochondrial efficiency, and stress-sensitive neural circuits involved in emotional processing. Central to this model is interoception, defined as the perception and integration of internal bodily signals. Interoceptive processing is here understood as a modulatory interface rather than a direct causal mechanism, shaped by metabolic signals, lipid availability, and individual neuroendocrine responsiveness. Empirical and clinical observations suggest heterogeneous emotional outcomes during IF. While some individuals report improved emotional clarity and regulatory capacity, others experience increased irritability, cognitive rigidity, or anxiety. These divergent responses appear to be mediated by interoceptive sensitivity, psychological history, and trait-level vulnerabilities such as perfectionism, anxiety sensitivity, or emotional suppression. Particular attention is given to potential clinical risks in individuals with eating disorder histories, trauma exposure, or heightened somatic vigilance, underscoring the importance of psychological screening when IF is considered in applied contexts. These observations should not be interpreted as clinical recommendations, but rather as emerging psychobiological patterns arising from the interaction between lipid metabolism, stress physiology, and emotional regulation. Current evidence is limited by a scarcity of longitudinal and integrative studies combining metabolic biomarkers with validated psychometric assessments. By integrating lipid metabolism with interoceptive and affective processes, future research adopting mixed-method designs may better clarify both the therapeutic potential and the psychological boundaries of intermittent fasting as a psychobiological intervention.