Metabolic regulation of synaptic plasticity in anorexia nervosa.

Anorexia nervosa (AN) is increasingly understood as a metabo-psychiatric disorder in which metabolic biology and neural circuit function are intrinsically intertwined. Genetic studies reveal that AN is associated with heritable metabolic traits suggesting that metabolic vulnerability contributes to the disorder. The metabolic profile of AN further shapes brain responses; endocrine signals such as insulin, leptin, ghrelin, and adiponectin elicit atypical neural responses in circuits regulating appetite, reward, interoception, and cognitive control. This altered signaling is accompanied by circuit-specific remodeling, suggesting that the chronic metabolic dysregulation seen in AN affects synaptic plasticity across distributed brain regions. Neural systems that integrate metabolic, emotional, and cognitive information-including hypothalamic, striatal, prefrontal, and limbic circuits-show altered plasticity under starvation. Glucose and insulin modulate excitatory-inhibitory balance and synaptic efficacy, while ketone bodies act as starvation-associated neuromodulators influencing transmitter release and structural plasticity. These and other body-to-brain signals recalibrate network dynamics central to food intake, motivation, and learning. At the molecular level, intracellular metabolic sensors such as AMPK, mTOR, and O-GlcNAc function as transducers that convert nutrient availability into changes in protein synthesis, receptor trafficking, and dendritic spine architecture, providing mechanistic links between metabolic state and synaptic remodeling. Overall, converging evidence supports a model in which AN arises from interactions between metabolic traits and the plastic neural circuits mediating food intake, emotion, and cognition. By clarifying how metabolic signals reshape synaptic ensembles in AN, we present a framework for understanding mechanisms of vulnerability and identify targets capable of restoring adaptive plasticity. This review suggests a trajectory in which treatments jointly address metabolic physiology and brain-based processes of learning, motivation, and affect.