In the modern world, improvements in human health can be offset by unhealthy lifestyle factors, including the deleterious consequences of stress and obesity. For energy homeostasis, humoral factors and neural afferents from the gastrointestinal tract, in combination with long-term nutritional signals, communicate information to the brain to regulate energy intake and expenditure. Energy homeostasis and stress interact with each other, and stress affects both food intake and energy expenditure. Prolactin-releasing peptide, synthesized in discrete neuronal populations in the hypothalamus and brain-stem, plays an important role in integrating these responses. This review describes how prolactin-releasing peptide neurons receive information concerning both internal metabolic states and environmental conditions, and play a key role in energy homeostasis and stress responses.