[Methods of body composition and four compartiments model in obese school children]. / Métodos de composición corporal y modelo de cuatro compartimentos en escolares obesos chilenos.

INTRODUCTION: In Chile, the prevalence of obesity in schoolchildren is 21.3%. The study and individual intervention of this malnutrition, it is necessary to have not only global indicators of nutritional status, but also indicators that give information on body composition. OBJECTIVE: To compare estimates of body fat isotopic dilution, plethysmography and radiographic absorptiometry 4C model in overweight schoolchildren. METHODS: We worked with 61 obese (BMI ≥ p 95) of both sexes, between 8 and 13 years, enrolled in a school in a district of the city of Santiago. The multicompartmental body composition determination, considered isotopic dilution, plethysmography and radiographic absorptiometry. Using as a reference standard four compartment model of Fuller. RESULTS: In both sexes, the method showed better agreement with the reference of 4 compartments was isotope dilution (r = 0.98, p < 0.01). In children, the isotopic dilution underestimates body fat in -0.40 kg. By contrast, DEXA and plethysmography overestimate body fat by 0.81 kg and 1.89 kg respectively. In women, all methods overestimate body fat, with less emphasis isotopic dilution value 0.46 kg, 0.52 kg after DEXA and plethysmography 1.31 kg. CONCLUSIONS: The deuterium isotopic dilution would be the most sensitive method for estimating body fat in research studies because it shows the best agreement with the gold standard multicompartmental model.

Métodos de composición corporal y modelo de cuatro compartimentos en escolares obesos chilenos / Methods of body composition and four compartiments model in obese school children

Introducción: En Chile, la prevalencia de obesidad en los escolares es de 21,3%. El estudio y la intervención individual de esta malnutrición, hacen necesario contar no sólo con indicadores globales de estado nutricional, sino también, indicadores que entreguen información de la composición corporal. Objetivo: Comparar las estimaciones de la grasa corporal de dilución isotópica, pletismografía y absorciometría radiográfica con el modelo de 4C en escolares obesos. Métodos: Se trabajó con 61 niños obesos (IMC > p 95) de ambos sexos, entre 8 y 13 años, reclutados en un colegio de una comuna de la ciudad de Santiago. La determinación de composición corporal multicompartimental, consideró dilución isotópica, pletismografía y absorciometría radiográfica; utilizando como patrón de referencia el modelo de cuatro compartimentos de Fuller. Resultados: En ambos sexos, el método que mejor concordancia mostró con el referente de 4 compartimentos fue la dilución isotópica (r = 0,98; p < 0,01). En niños, la dilución isotópica subestima la grasa corporal en -0,40 kg. Al contrario, la absorciometría radiográfica y la pletismografía sobreestiman la grasa corporal en 0,81 kg y 1,89 kg respectivamente. En mujeres, todos los métodos sobreestiman la grasa corporal, destacando con un menor valor la dilución isotópica (0,46 kg), luego la absorciometría radiográfica (0,52 kg) y la pletismografía (1,31 kg). Conclusiones: La dilución isotópica con deuterio sería el método más sensible para estimar grasa corporal en estudios de investigación ya que muestra la mejor concordancia con el gold estándar del modelo multicompartimental (AU)

Introduction: In Chile, the prevalence of obesity in schoolchildren is 21.3%. The study and individual intervention of this malnutrition, it is necessary to have not only global indicators of nutritional status, but also indicators that give information on body composition. Objective: To compare estimates of body fat isotopic dilution, plethysmography and radiographic absorptiometry 4C model in overweight schoolchildren. Methods: We worked with 61 obese (BMI > p 95) of both sexes, between 8 and 13 years, enrolled in a school in a district of the city of Santiago. The multicompartmental body composition determination, considered isotopic dilution, plethysmography and radiographic absorptiometry. Using as a reference standard four compartment model of Fuller. Results: In both sexes, the method showed better agreement with the reference of 4 compartments was isotope dilution (r = 0.98, p < 0.01). In children, the isotopic dilution underestimates body fat in -0.40 kg. By contrast, DEXA and plethysmography overestimate body fat by 0.81 kg and 1.89 kg respectively. In women, all methods overestimate body fat, with less emphasis isotopic dilution value 0.46 kg, 0.52 kg after DEXA and plethysmography 1.31 kg. Conclusions: The deuterium isotopic dilution would be the most sensitive method for estimating body fat in research studies because it shows the best agreement with the gold standard multicompartmental model (AU)