Energy requirements derived from total energy expenditure and energy deposition during the first 2 y of life

Background: Current recommendations for energy intake of children are deriv ed from observed intakes. Deriving energy requirements on the basis of ener gy expenditure and deposition is scientifically more rational than is using the observational approach and is now possible with data on total energy e xpenditure (TEE), growth, and body composition. Objectives: The objectives of this study were 1) to define energy requireme nts during the first 2 y of life on the basis of TEE and energy deposition; 2) to test effects of sex, age, and feeding mode on energy requirements; a nd 3) to determine physical activity. Design: TEE, sleeping metabolic rate, anthropometry, and body composition w ere measured in 76 infants. TEE was measured with doubly labeled water, sle eping metabolic rate with respiratory calorimetry, and body composition wit h a multicomponent model. Results: Total energy requirements were 2.23, 2.59, 2.97, 3.38, 3.72, and 4 .15 MJ/d at 3, 6, 9, 12, 18, and 24 mo, respectively. Energy deposition tin MJ/d) decreased significantly over time (P = 0.001) and was lower in breas t-fed than in formula-fed infants (P = 0.01). Energy requirements were appr oximate to 80% of current recommendations. Energy requirements differed by age (P = 0.001), feeding group (P = 0.03), and sex (P = 0.03). Adjusted for weight or fat-free mass and fat mass, energy requirements still differed b y feeding group but not by age or sex. Temperament and motor development di d not affect TEE. Conclusion: The TEE and energy-deposition data of these healthy, thriving c hildren provide strong evidence that current recommendations for energy int ake in the first 2 y of life should be revised.