Autoimmune encephalitides, particularly anti-N-methyl-D-aspartate receptor (anti-NMDA-R) encephalitis, have emerged over the last two decades as critical causes of acute neuropsychiatric syndromes and refractory epilepsy across pediatric and adult populations. Parallel to this growing recognition of immune-mediated mechanisms in neurological disease, renewed scientific interest has focused on the ketogenic diet as a metabolism-based therapy for epilepsy, including its application in super-refractory status epilepticus. Although traditionally conceptualized as distinct therapeutic domains—immunotherapy for autoimmune encephalitis and dietary manipulation for epilepsy—an expanding body of evidence suggests substantial mechanistic convergence between immune dysregulation, neuroinflammation, synaptic dysfunction, and metabolic interventions. This article synthesizes evidence from foundational clinical case series, immunopathological analyses, and experimental studies to construct an integrated theoretical framework linking autoantibody-associated encephalitis, inflammatory epileptogenesis, and ketogenic diet mechanisms. Drawing strictly on the provided references, this work explores how antibodies targeting synaptic receptors disrupt neuronal networks, how inflammation contributes to seizure generation and persistence, and how ketogenic diets modulate neural excitability, inflammatory pathways, and the gut–brain axis. By offering an extensive theoretical elaboration of existing findings rather than a superficial summary, the article addresses critical gaps in the literature regarding interdisciplinary integration. The analysis emphasizes clinical implications for pediatric epilepsy, super-refractory status epilepticus, and autoimmune encephalitis, while also identifying limitations in current knowledge and outlining future research directions. Ultimately, this work argues that metabolism-based dietary therapies may represent a valuable adjunctive strategy within a broader immunometabolic approach to neuroinflammatory and autoimmune epilepsies.