NPY and hyperprolactinemia: For example, risperidone increases food intake and induces weight gain, glucose intolerance, hypertriglyceridemia, and hyperprolactinemia.8, 9, 10 Previous research has suggested that risperidone induces weight gain by upregulating the expression of hypothalamic histaminergic H1 receptors and neuropeptide Y (NPY).11 Central NPY signaling is known to play a critical role in the regulation of food intake and energy balance,12 suggesting that preventing or reversing the increase in NPY expression may help reduce risperidone‐induced weight gain.