Short-term growth and substrate use in very-low-birth-weight infants fed formulas with different energy contents

Background: Currently available preterm formulas with energy contents of 33 50 kJ (800 kcal)/L promote weight and length gain at rates at or above intr auterine growth rates but disproportionately increase total body fat. Objective: The objective of this study was to determine whether fat accreti on in formula-fed, very-low-birth-weight (VLBW) infants could be decreased and net protein gain maintained by reducing energy intakes from 502 kJ (XO kcal).kg(-1).d(-1) [normal-energy (NE) formula] to 419 kJ (100 kcal).kg(-1) .d(-1) [low-energy (LE) formula] while providing similar protein intakes (3 .3 g.kg(-1).d(-1)). Design: The study was a randomized, controlled trial enrolling 20 oppropria te-for-gestational-age (AGA) and 16 small-for-gestational-age (SGA) VLBW in fants (mean birth weight: 1.1 kg; mean gestational age: 31 wk); energy expe nditure and nutrient balance were measured at 4 wk of age and anthropometri c measurements were made when infants weighed 2 kg. Results: The percentage of fat in newly formed tissue was significantly low er in AGA infants fed the LE formula (n = 9) than in those fed the NE formu la (n = 10) (9% compared with 23%; analysis of variance, P = 0.001). Energy expenditure was higher in AGA infants fed the NE formula than in those fed the LE formula. Skinfold thickness was markedly lower in AGA infants fed t he LE formula than in those fed the NE formula, resulting in a lower estima ted percentage body fat (8.0 +/- 1.9% and 10.8 +/- 3.5%, respectively; P < 0.05). Three of 6 SGA infants fed the LE formula were excluded during the s tudy because of poor weight gain. Conclusions: Body composition can easily be altered by changing the energy intakes of formula-fed VLBW infants. Energy intakes in these infants should be >419 kJ (100 kcal).kg(-1).d(-1).