A 19-year-old female presented with acute onset of bizarre behavior, confusion, auditory hallucinations, and delusions after two weeks on a 100 kcal/day diet. She had a normal neurological examination. Urinalysis showed ketones 4+. She had elevated antinuclear antibody (ANA) (320) and positive heterozygous factor V Leiden mutation. Magnetic resonance imaging brain scan showed hyperintensity in the ventroanterior nucleus of the left thalamus. Ventroanterior thalamic stroke has been associated with personality changes. This is the first case of starvation-induced thalamic psychosis in the setting of factor V Leiden mutation and elevated ANA. The patient improved with risperidone in one month.