This chapter focuses on the advances in understanding pig nutritional requirements and metabolism. The authors begin by outlining optimising sow nutrition throughout gestation and lactation, covering the management of gilt weight on herd entry, nutrition to prevent sow lameness, minimising variation in nutrient intake during gestation, the transition from gestation to lactation, maintaining body weight during lactation, and nutritional interventions to improve productivity of the gilt, sow and litter. They then discuss reducing variation in pig production systems, and the strategic use of metabolic modifiers and other modes of growth promotion. The authors next examine matching nutrient requirements to diet specifications, covering the rapid measurement of nutritional quality, updated information on nutritional requirements, and water requirements for pigs. They then describe optimising the utilisation of co-products, as well as gut health, nutrient utilisation capacity and health interactions. Finally future trends in the field of nutritional requirements are considered.