This work aims to prepare silymarin (SIL)-loaded chitosan (CH) nanoparticles (SIL-CH NPs) as a new weight loss agent, which was formulated by loading the SIL particle on chitosan NPs to expand anti-dyslipidemia effects and improve hypothalamic NPY level of SIL in a rat model of diet-induced hyperlipidemia. The gene discussed is NPY; the disease is hyperlipidemia.