This article provides a comprehensive review on the nutritional management of preterm infants. The review also describes the methodology developed and implemented in the BabyGrow longitudinal nutrition and growth study to assess the nutritional status of preterm infants. Nutrient intake data revealed substantial cumulative protein deficits, which persisted for at least 5 weeks of life at the same time as energy excesses were accumulating. These data show that actual nutrient intake assessment is important for developing effective nutritional strategies. Postnatal growth was evaluated, and body composition was assessed by air displacement plethysmography up to 2 months corrected age.