Accuracy of standardized equations for predicting metabolic rate in premenarcheal girls.

Several different equations based on height, weight, sex, and age are available to predict metabolic rate in children and adolescents. The purpose of this study was to determine which of the published standardized equations most accurately predicts metabolic rate in premenarcheal girls. Resting metabolic rate (RMR) was measured in 186 premenarcheal girls by using open-circuit indirect calorimetry with a ventilated hood. Measured RMR was compared with equations provided by the FAO/WHO/UNU, the Mayo Clinic, and Robertson and Reid for girls of the same age. The accuracy of each equation differed for each Tanner stage. The Mayo Clinic standards significantly differed from measured RMR among girls in Tanner stages 1 and 2. The Robertson and Reid standards differed from measured RMR for girls in Tanner stage 1. Only the FAO/WHO/UNU equation predictions did not differ from measured RMR for all Tanner stages studied. These results indicate that the FAO/WHO/UNU equation is the best predictor of RMR in premenarcheal girls at different stages of development. Furthermore, because RMR measured under inpatient and outpatient conditions did not differ significantly, an overnight measurement is not necessary for a reliable determination of RMR.

Effect of sedentary activities on resting metabolic rate.

We examined the effect of television viewing on resting metabolic rate (RMR) in a cohort of 9 obese and 18 nonobese girls aged 10.4 +/- 1.1 y. RMR was measured while girls watched television, read, or sat quietly for 15 min. Movement was assessed by using activity monitors and a manual count of movements observed on a videotape. Absolute RMR was greater for the obese girls, but no significant treatment effect existed for absolute RMR within either group. Although measured activity did not differ, observed movements were greater when the girls were sitting quietly. Total observed and measured movements were significantly correlated with the CV of the minute-by-minute RMR. These results suggest that television viewing does not alter RMR. Although children appear to fidget more when sitting quietly than when they read or watch television, fidgeting appears to affect the minute-to-minute variation of RMR rather than the level of resting energy expenditure.

Estimation of energy requirements in persons with severe central nervous system impairment.

We measured resting metabolic rate (RMR) in 12 persons (aged 10 to 30 years) with severe impairment of the central nervous system requiring gastrostomy feedings, and compared our findings with the RMR predicted from standardized equations. The RMR was 70.6% +/- 15.7% of that predicted from the Mayo Clinic nomogram, 63.7% +/- 18% of that predicted from the Food and Agriculture Organization/World Health Organization/United Nations University equation, and 75.4% +/- 17.3% of that predicted from the Robertson and Reid equation. Energy intake was 756 +/- 225 kcal/day and RMR was 708 +/- 231 kcal/day; RMR adjusted for changes in body energy stores was 729 +/- 231 kcal/day. No significant differences were found between energy intake and RMR, or between energy intake and the sum of RMR and changes in body energy stores. These findings demonstrate that standardized equations overestimate energy needs of individuals with severe CNS impairment. Measures of energy intake adjusted for weight changes represent a valid method to determine energy requirements in a group of individuals with severe CNS impairment. Length was found to be significantly correlated with RMR (r = 0.79; p < 0.01). When the regression equation was tested on another group of subjects from the same residential facility, the equation predicted energy needs reasonably well for those individuals with similar energy intakes but not for all patients with CNS disorders.