Abstract: The brain performs extraordinary computations while consuming remarkably little energy, yet we still know surprisingly little about how energy availability shapes brain function. My research program seeks to understand the brain by investigating how neural circuits monitor, allocate, and utilize energy across the body. By combining innovative imaging technologies, chemical biology, and neural circuit mapping, we have uncovered previously unknown pathways linking metabolism, behavior, and brain activity. These discoveries reveal fundamental principles of brain–body communication and may ultimately provide new opportunities to understand and treat obesity, diabetes, neurodegenerative disorders, and other diseases shaped by metabolic dysfunction.