Preterm infant nutritional compositions comprising beta-hydroxy-beta-methylbutyric acid for supporting growth, accretion of lean body mass, and a healthy body composition in preterm infants are provided. The preterm infant nutritional compositions may be liquid formulas, fortifiers, and supplements. Methods for supporting growth, accretion of lean body mass, and a healthy body composition in a preterm infant are also provided. The methods include administering a preterm infant nutritional composition comprising beta-hydroxy-beta-methylbutyric acid to the preterm infant.
