Body Fat Cutoffs Measured by Isotopic Dilution With Deuterium Oxide in Adolescents.

Abstract

Objective: To establish nutritional diagnosis and provide a series of reference body fat percentiles for age and sex in adolescents using isotopic dilution with deuterium oxide, a method considered the gold standard for assessing body composition. After obtaining data on weight and height, Method: among participants aged 10 to 14 years, the Body Mass Index (BMI) was calculated, used to obtain the nutritional diagnosis. The analysis of body composition was performed on a saliva sample collected before and after the administration of a dose of Deuterium Oxide (D2O, at a dose of 0.5g/kg (maximum 30g), using the technique of Infrared Spectrometry by Transform of Fourier (FTIR), following the methodology described by Slater et al., (2005). Study approved by the Institutional Research Ethics Committee. The Results: sample consisted of 390 participants, 233 (59.8%) girls, with a mean age of 12.7 ±1.1 years. The percentage of body fat by D2O showed a parametric distribution between males and females, with a mean of 21.7±9.4%BF and 28.7±8.1%BF, respectively. Conclusion: The prevalence of overweight was 15.6% and 1.5% with obesity. There is a trend towards an increase in %BF in female quartiles and a reduction in %BF in all male quartiles. Girls enter adolescence (10 years old) with a statistically lower amount of body fat than in the intermediate period of this phase. This did not occur in boys, who remained with the same absolute value of body fat. Girls are classied as overweight when they reach 1/3 of their weight consisting of fat.