Microbial catalysts must partition incoming substrate between the synthesis of biomass and the synthesis of a desired product. Although biomass synthesis generates more catalyst and therefore potentially higher volumetric productivities, the synthesis of product increases specific production rates and product yields. Two-stage bioprocesses can accommodate this tradeoff through temporal separation of the growth and production phases. The biocatalyst first grows to optimal density; it is then switched to a growth-arrested state during which the product is synthesized. However, a substantial reduction in metabolic activity is often observed during cellular growth arrest, even in the presence of sufficient substrate. An ultimate bioengineering goal, therefore, is to create growth-arrested states that retain high metabolic activity. Achieving this goal brings the metabolic engineer to the intersection of microbial physiology, synthetic biology and biochemistry. In this Review, we describe various aspects of the design of microbial catalysts for two-stage bioprocesses for metabolite production, including synthetic biology tools to arrest cell growth using external or internal cues, and metabolic engineering tools to minimize interference from the native metabolic network and enhance substrate uptake and conversion. We highlight recent systems biology studies of nutrient-limited heterotrophs and phototrophs and conclude that the reduction in substrate uptake by cells in growth arrest is the consequence of reduced energy demand as well as imbalances in regulatory metabolites that typically arise during nutrient limitation. On the basis of these studies, we propose strategies for increasing metabolic activity in growth-arrested cells.