Total energy expenditure in 4- to 6-yr-old children.

There is a sparsity of data on energy expenditure in young children. We therefore examined the components of daily energy expenditure in a group of 30 children (16 boys, 14 girls; age 4-6 yr) characterized for body weight, height, heart rate, and body composition from bioelectrical resistance. Total energy expenditure (TEE) was measured over 14 days under free living conditions by doubly labeled water, resting energy expenditure (REE) from indirect calorimetry, and activity energy expenditure was estimated from the difference between TEE and REE. Mean TEE was 1,379 +/- 290 kcal/day, which was 475 +/- 202 kcal/day lower than energy intake recommendations for this age group. Activity-related energy expenditure was estimated to be 267 +/- 203 kcal/day. TEE was most significantly related to fat-free mass (FFM; r = 0.86; P < 0.001), body weight (r = 0.83; P < 0.001), and REE (r = 0.80; P < 0.001). When TEE was adjusted for FFM, a significant correlation with heart rate was observed (partial r = 0.54; P = 0.002). Collectively, 86% of interindividual variation in TEE was accounted for by FFM, heart rate, and REE. We conclude that, in young 4- to 6-yr-old children, 1) TEE is approximately 25% lower than current recommendations for energy intake and 2) combined measurement of FFM, heart rate, and REE explain 86% of interindividual variation in TEE, thus providing a possible alternative method to estimate TEE in young children.