The neuroendocrine system is a two-way communication between the nervous and endocrine systems, enabling homeostatic regulation across a wide range of physiological and clinical conditions. This enables integration of central neural circuits with peripheral hormonal signals and aids in modulation of vital physiological functions such as energy balance, metabolic stability, fluid regulation, and stress responses, among others. This chapter discusses the adaptive neuroendocrine responses that occur during exercise, pregnancy, starvation, obesity, anorexia nervosa, and chronic renal failure. It further outlines key neuroendocrine diseases and disorders of energy homeostasis, hypothalamic–pituitary–adrenal (HPA) axis dysregulation, and neuroendocrine tumors.