New equations to estimate basal metabolic rate in children aged 10–15 years

Abstract

Objective: To develop new equations for the estimation of basal metabolic rate in children aged 10–15 years, and to evaluate the impact of including pubertal stage into the equations.

Design: Mixed longitudinal.

Setting: The children were recruited from schools in Oxford, and the measurements were made in the schools.

Subjects: 195 school children, aged 10–15 years, were recruited in three cohorts. The gender distribution of the subjects was 40% boys and 60% girls.

Methods: Basal metabolic rate (BMR) was measured, by indirect calorimetry, at 6-monthly intervals for 3 years. Anthropometric data, height, weight, body breadths and skinfold measurements (biceps, triceps, subscapular, suprailiac and medial calf) were collected on each occasion. Fat and fat-free mass was calculated from the skinfold measurements. Pubertal development was also assessed on annually by paediatricians. Pubic hair (PH) and gonad (G) development was assessed in boys and breast (B) development in girls. The girls were questioned about menarche. Stepwise multiple regression analysis was used to develop and assess new formulae for BMR that also incorporate pubertal development.

Results: The mean BMR measured was 5.754 (s.d. 0.933) MJ/day (138 (s.d. 22) kJ/kg body wt/day) in the boys (n=351) and 5.476 (s.d. 0.725) MJ/day (121 (s.d. 20) kJ/kg body wt/day) in the girls (n=554). Weight was the most important factor in developing the regression equations for the calculation of BMR in both sexes (R²=0.61 and 0.52 for boys and girls, respectively). Stepwise multiple regression analyses, with independent variables such as gender, weight, height, puberty stage and skinfolds, allowed several BMR regression equations to be developed. The inclusion of the menarche status in the regression equations significantly (P<0.05) improved BMR estimation in the pre-menarche girls. Boys, pubertal stage as assessed by Pubic Hair (PH) and Gonadal Stage (G) did not contribute to a significant improvement in BMR estimation, except for 11-year-olds.

Conclusions: The inclusion of pubertal stage afforded only minor improvements in the derivation of regression equations for the estimation of BMR of children aged between 10 and 15 years.

Sponsorship: Nestlé Foundation, Lausanne, Switzerland.

Descriptors: