The generation of neurons in the developing and adult mammalian brain by neural stem/progenitor cells (NSPCs) depends on a tight control of NSPC activity and neuronal differentiation that is regulated by a plethora of intrinsic and extrinsic molecular cues. Besides well-studied morphogenic signaling pathways and transcriptional codes that govern the distinct developmental steps from the dividing NSPC to a functional neuron, a critical role of cellular metabolism to determine the functional properties of NSPCs and newborn neurons has been recently identified. Here, we review advances in our understanding of how metabolism affects NSPC behavior and subsequent neuronal differentiation and suggest how metabolism may serve as a common signal integrator to ensure life-long addition of new neurons in the mammalian brain.