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Resting metabolic rate in six- to ten-year-old obese and nonobese children
C Maffeis1, Y Schutz, R Micciolo
1Regional Centre for Juvenile Diabetes, Institute of Pediatrics-University of Verona Policlinico, Italy.
Insights
Resting metabolic rate (RMR) in children is best predicted by fat-free mass. New predictive equations for RMR in prepubertal boys and girls were developed, showing current formulas may overestimate metabolic rates.
Area of Science:
- Pediatric Endocrinology
- Human Physiology
- Body Composition Analysis
Background:
- Accurate assessment of resting metabolic rate (RMR) is crucial for understanding energy balance in children.
- Obesity prevalence in children necessitates reliable methods for estimating metabolic demands.
- Existing RMR predictive equations may not accurately reflect metabolic rates in prepubertal populations.
Purpose of the Study:
- To assess resting metabolic rate (RMR) and body composition in obese and nonobese prepubertal children.
- To identify key predictors of RMR in this age group.
- To develop and validate new RMR predictive equations for boys and girls aged 6-10 years.
Main Methods:
- Indirect calorimetry was used to measure RMR in 130 children (62 boys, 68 girls).
- Skin-fold thickness was employed for body composition assessment.
- Step-down multiple regression analysis was performed using age, gender, weight, and height as variables.
Main Results:
- Fat-free mass emerged as the strongest single predictor of RMR (R² = 0.64).
- Specific predictive equations were derived for boys (R² = 0.58) and girls (R² = 0.69).
- Existing RMR prediction formulas frequently overestimated measured RMR, particularly in overweight children.
Conclusions:
- Fat-free mass is a primary determinant of RMR in prepubertal children.
- The developed equations offer improved RMR prediction for boys and girls in the studied age range.
- Clinicians should be cautious when using general RMR prediction formulas for pediatric populations, especially those who are overweight.
Abstract:
The resting metabolic rate (RMR) and body composition of 130 obese and nonobese prepubertal children, aged 6 to 10 years, were assessed by indirect calorimetry and skin-fold thickness, respectively. The mean (+/- SD) RMR was 4619 +/- 449 kJ.day-1 (164 +/- 31 kJ.kg body weight-1 x day-1) in the 62 boys and 4449 +/- 520 kJ.day-1 (147 +/- 32 kJ.kg body weight-1 x day-1) in the 68 girls. Fat-free mass was the best single predictor of RMR (R2 = 0.64; p < 0.001). Step-down multiple regression analysis, with independent variables such as age, gender, weight, and height, allowed several RMR predictive equations to be developed. An equation for boys is as follows: RMR (kJ.day-1) = 1287 + 28.6 x Weight(kg) + 23.6 x Height(cm) - 69.1 x Age(yr) (R2 = 0.58; p < 0.001). An equation for girls is as follows: RMR (kJ.day-1 = 1552 + 35.8 x Weight (kg) + 15.6 x Height (cm) - 36.3 x Age (yr) (R2 = 0.69; p < 0.001). Comparison between the measured RMR and that predicted by currently used formulas showed that most of these equations tended to overestimate the RMR of both genders, especially in overweight children.