The ability of an organism to convert organic molecules from the environment into energy is essential for the development of cellular structures, cell differentiation and growth. Mitochondria have a fundamental role in regulating metabolic pathways, and tight control of mitochondrial functions and dynamics is critical to maintaining adequate energy balance. In complex organisms, such as mammals, it is also essential that the metabolic demands of various tissues are coordinated to ensure that the energy needs of the whole body are effectively met. Within the arcuate nucleus of the hypothalamus, the NPY-AgRP and POMC neurons have a crucial role in orchestrating the regulation of hunger and satiety. Emerging findings from animal studies have revealed an important function for mitochondrial dynamics within these two neuronal populations, which facilitates the correct adaptive responses of the whole body to changes in the metabolic milieu. The main proteins implicated in these studies are the mitofusins, Mfn1 and Mfn2, which are regulators of mitochondrial dynamics. In this Review, we provide an overview of the mechanisms by which mitochondria are involved in the central regulation of energy balance and discuss the implications of mitochondrial dysfunction for metabolic disorders.