Intermittent Fasting and Emotional Regulation: A Psychobiological Framework Integrating Metabolic, Neuroendocrine and Interoceptive Mechanisms.

<b>Background/Objectives</b>: Intermittent fasting (IF) has been widely investigated for its metabolic effects, including improvements in insulin sensitivity, lipid metabolism, and inflammatory markers. However, its psychological and experiential dimensions remain comparatively underexplored. The present narrative review examines IF within a psychobiological framework, integrating evidence from metabolic science, neuroendocrinology, and affective neuroscience to explore its potential impact on emotional regulation and interoceptive processes. <b>Methods</b>: A structured narrative literature search was conducted across PubMed, Scopus, and Google Scholar, focusing on studies published between 2010 and 2025. Eligible studies included human and relevant animal research addressing metabolic, hormonal, interoceptive, and psychological responses to IF. Evidence was synthesized thematically to identify convergent mechanisms linking metabolic adaptations to emotional and regulatory outcomes. <b>Results</b>: Available literature suggests that IF is associated with a metabolic shift toward lipid utilization, characterized by increased ketone body production, particularly β-hydroxybutyrate. These adaptations appear to be accompanied by modulation of neuroendocrine pathways and may influence central nervous system functioning through mechanisms potentially related to neuroinflammation, mitochondrial efficiency, and synaptic plasticity. Emerging evidence further suggests that IF may modulate BDNF signaling and gut-brain axis activity, although direct causal pathways in humans remain to be established. At the psychological level, IF is associated with heterogeneous emotional outcomes: structured fasting protocols have been linked to modest improvements in perceived stress and mood in metabolically healthy individuals, whereas irritability, anxiety, or behavioral rigidity may emerge in those with pre-existing psychological vulnerabilities. Individual differences in interoceptive sensitivity, emotion regulation strategies, and moderating biological factors-including sex, circadian timing, and habitual physical activity-appear to influence these responses. <b>Conclusions</b>: Overall, IF may be conceptualized as a context-dependent psychobiological stressor whose effects extend beyond metabolic regulation to include interoceptive and emotional processes. These effects appear bidirectional, potentially promoting psychological resilience in some individuals while increasing the risk of affective destabilization or maladaptive behaviors in others. Current evidence remains limited by a lack of integrative and longitudinal studies combining metabolic and psychological measures. Future research adopting multidisciplinary approaches is needed to clarify the mechanisms underlying individual variability and to better define the potential benefits and risks of IF in both clinical and non-clinical populations.