Determinants of resting energy expenditure in obese and non-obese children and adolescents

Abstract

Resting energy expenditure (REE) is the largest component of total daily energy expenditure. Objectives of this study were to examine whether differences in REE exist after obesity develops in a group of children and adolescents, and to determine the effects of body composition, gender, age, pubertal development and parental obesity on REE. In 116 Caucasian children and adolescents (57 obese and 59 non-obese), aged 7.8 to 16.6 years, REE was assessed by open-circuit indirect calorimetry and different anthropometric variables and bioelectrical impedance were obtained (weight, height, skinfold thicknesses, waist and hip circumferences). Anthropometric indices and body compartments were calculated: the body mass index, surface area (SA), fat-free mass (FFM), fat-mass (FM) and percentage of FM. Differences between obese and non-obese subjects were tested and stepwise multiple regression analysis was performed with REE as dependent variable. Results show that REE was significantly higher in obese than in non-obese children and adolescents but REE/FFM ratio was not significantly different between these groups. In the non-obese group, FFM explained 73.1% of the variability in REE and gender, age and SA added 3.8%, 2.6%, and 2.6% to it, respectively. In the obese group, FFM was also the most powerful predictor of REE with 72.3%, followed by waist circumference and age with 2.5% and 2.1%, respectively. These results show that REE differences between obese and lean children do not seem to justify the maintenance of obesity. The main determinant of REE is FFM in both groups. No significant contribution of FM, pubertal development or parental obesity in REE was found in children and adolescents.

Energy Prediction Equations Are Inadequate for Obese Hispanic Youth

“…The failure to detect differences may be due to the small sample size tested. The average REE in this study, measured using breath-by-breath analysis, was higher than the 22–26 kcal/kg per day reported for studies of obese children measured using a head canopy in which exhaled air from multiple breath cycles was intermingled and sampled (30,33). The measured REE for 7–8 y youth was lower than normal-weight values (boys/girls) of 51/44 kcal/kg per day for 3–8 y (1), which was expected since the comparison group included younger children who have higher metabolic rates.…”

“…Mean REE was nearly that of normal-weight values (boys/girls) of 37/33 kcal/kg per day for 9-13 y and 29/25 kcal/kg per day for 14–18 y (1). Weight-adjusted REE was expected to be lower for obese individuals than for healthy-weight children (28,30,33) because fat tissue is substantially less metabolically active than LBM, and fat mass contributes proportionately more to the total body weight in obesity. To our knowledge, only one study tested differences in REE (24-hour kcal/kg total body weight) as a factor of obesity.…”

“…To our knowledge, only one study tested differences in REE (24-hour kcal/kg total body weight) as a factor of obesity. Among 7–16 y white Spanish children, REE averaged 25.9±4.4 versus 33.3±5.3 kcal/kg per day (P<0.001) for obese (n=57) and non-obese (n=59) participants, respectively (30). Other studies also indicated an average 7–10 kcal/kg per day lower REE in obese than normal-weight children (6,24,28,34).…”

Effects of supplemental fish oil on resting metabolic rate, body composition, and salivary cortisol in healthy adults

“…The failure to find an increase in RMR following fish oil treatment is hard to explain given the significant increase in lean mass observed in the present study. Several studies have shown that lean mass is the largest determinant of RMR [28-30], and decreasing lean mass decreases RMR [31], while increasing lean mass increases RMR [32]. Therefore, it would be expected that the increase in lean mass would correspond to an increased RMR following fish oil treatment.…”

Contributing factors and variability of energy expenditure in non-obese, obese, and post-obese adolescents

“…The main significant determinant of BMR is FFM (R 2 = 0.65-0.80 [24,25]), whereas FM is significant only in obese subjects (R 2 < 0.04, [24,26]). Sex is also a significant determinant of BMR (0.02 < R 2 < 0.04, [24]): after adjustment for body composition, BMR is significantly higher in boys than in girls, by 3% and 6% in prepubertal and pubertal subjects, respectively [24,27,28], because of (1) higher proportions of skeletal glycolytic fibres [29], and higher Na + -K + ATPase activity [30], and (2) changes in hormonal status [19].…”