The relationship between organ-tissue body composition and resting energy expenditure in prepubertal children

Taishi Midorikawa,Yuki Hikihara,Shizuo Sakamoto,Megumi Ohta,Suguru Torii,Takafumi Ando,Shigeho Tanaka

doi:10.1038/s41430-018-0344-2

Abstract

Background/ObjectivesIn this study, we ascertained the relationship between resting energy expenditure (REE) obtained using two procedures: indirect calorimetry and from organ-tissue mass, calculated employing magnetic resonance imaging (MRI), and adult metabolic rate constants, in prepubertal children. Differences between the measured and the calculated REEs were assessed according to age at puberty approaching stage.Subjects/MethodsWe recruited 6–12 years old 110 healthy Japanese prepubertal children (40 girls and 70 boys). Organ-tissue masses for different organs (skeletal muscle, liver, kidneys, brain and adipose tissue) were determined using MRI and dual-energy X-ray absorptiometry. Heart and residual masses were calculated on the basis of each equation. REE was measured using the Douglas bag technique (measured REE). On the other hand, calculated REE was obtained by multiplying the sum of body compartments with the corresponding adult tissue respiration rate.ResultsThe measured REE was significantly greater than the calculated REE in both, boys and girls, although a significant association was noticed between the two REEs in both the sexes. Besides, correlation between age and difference in the two REEs was found to be significant only in girls.ConclusionsThe present study revealed that: (1) measured and calculated REEs differ by approximately 300 kcal/day in a relatively large sample of prepubertal children, and (2) the difference in organ-tissue mass between the measured and calculated REEs increased from approximately 200 to 400 kcal/day during the developmental process in girls but not in boys.

Highlights

Children have lower body mass and fat-free mass (FFM) than adults, but their absolute resting energy expenditure (REE, kcal/day) is comparable with that in adults
A significant association between the measured and calculated REEs was noticed in the two groups (r = 0.83, p < 0.01 for boys and r = 0.82, p < 0.01 for girls) (Fig. 1)
Age was significantly correlated with the differences in measured and calculated REEs in the girls but not in the boys (Fig. 3)

Summary

Introduction

Children have lower body mass and fat-free mass (FFM) than adults, but their absolute resting energy expenditure (REE, kcal/day) is comparable with that in adults. The variation in REE is due to variable organ-tissue mass [2,3,4]. A previous study reported that the high REE (i.e., mean measured REE, 2286 kcal/day) seen in sumo wrestlers is probably not because of an elevated organ-tissue metabolic rate but due to an increased volume of tissue with lowand high-metabolic activity [5]. According to a recent study, training for aerobic endurance has no role to play in the chronic increase in adult resting metabolic rate, in people with a VO2peak of about 60 ml/(min kg) [6]. The individual variation is minimal, the organ-tissue metabolic rate would be almost constant for the variability in adults

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Results

Conclusion