Body composition in 5–18-y-old obese children and adolescents before and after weight reduction as assessed by deuterium dilution and bioelectrical impedance analysis

Abstract

The aim of the present study was to develop an equation for the prediction of total body water (TBW) from bioelectrical impedance analysis (BIA) in obese children and adolescents before and after weight reduction. In 146 obese subjects with a mean age of 12.7 +/- 3.0 y (5.5-17.8 y), TBW was measured by using deuterium dilution as well as the resistance index (RI; ht2/resistance) using BIA before and after weight loss. Initially, the RI correlated well with measured TBW (r2 = 0.92, P < 0.001). A multiple-regression analysis using forward stepwise selection of the variables RI, sex, age, weight, height, and waist-hip ratio revealed that the equation TBW = 0.35 x RI + 0.27 x age + 0.14 x weight - 0.12 predicts most accurately individual values of TBW before weight loss (adjusted r2 = 0.96, SEE = 1.9 L) with a mean error of predicted TBW of 1.40 +/- 1.38 L. This equation was validated in 1000 random samples (bootstrap-sampling method), giving a mean r2 of 0.95. During the weight-reduction program, which included an energy-restricted diet and an extensive exercise program, the patients lost 7.7 +/- 3.2 kg, leading to a small decrease in TBW of 0.4 +/- 1.5 L. When the developed prediction equation was applied to the data after weight loss, an r2 value of 0.94 between measured and calculated TBW and a mean error of 2.18 +/- 1.89 L was obtained. Validation of the equation in 1000 random samples after weight loss again gave a mean r2 value of 0.95. Individual changes in predicted TBW correlated only weakly with those of measured TBW (r = 0.21, P < 0.05). Thus, individual TBW values before and after weight loss can be predicted by BIA with acceptable accuracy by using the developed equation. However, prediction of small individual changes in TBW during weight loss is not possible by BIA.

Safety and efficacy of treatment with an ephedrine/caffeine mixture. The first double-blind placebo-controlled pilot study in adolescents

“…Skinfold thickness measurements (triceps, biceps, supra-iliac, sub-scapular and calf) were performed in triplicate on the left side of the body using Holtain calliper. Body composition was determined by the analysis of bioelectric impedance (BIA 101, RJL Systems, Detroit), using the equations of Wabitsch et al 7 Waist : hip ratio (WHR) was calculated as the ratio of the minimal waist circumference to the circumference of the maximal gluteal protuberance to assess body fat distribution.…”

Obesity and blood pressure—results from the examination of 2365 schoolchildren in Germany

“…Hypertension was defined as diastolic blood pressure above the 95th reference percentile, 19,20 using the reference values of Sörgel et al 21 Body fat was calculated from BIA according to Wabitsch et al 22 …”

Validating a practical approach to determine weight control in obese children and adolescents

“…Equations for obese children and adolescents have been utilized in a few studies. 12,33,34 For example, Wabitsch et al 12 developed equations for the prediction of total body water from BIA in young obese subjects before and after weight loss. They used a multiple regression analysis with forward stepwise selection of the independent variables including the waist-to-hip ratio.…”

“…10 UWW is often considered the gold standard for adults. 11 Studies to validate body composition methods in growing children are limited 9 and particularly with obese subjects, 12 but much of the past pediatric research has been based on UWW, and most body assessment techniques have been validated against this procedure. 13 Neither UWW nor BIA are readily available in most clinical settings.…”