SPEG and neurodegenerative disease: Acetamidobenzoic acid, a metabolite associated with high-fiber diet, can target SPEG (6CY6) protein in the hippocampus, thereby affecting autophagic homeostasis in the hippocampus, regulating the hippocampal–hypothalamic endocrine axis and eventually improving the diabetic and neurodegenerative disease states of patients with obesity.