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

Abstract

To study the usefulness of a mathematical index for assessing changes in body composition of obese children and adolescents who undergo a weight control program. A short-term longitudinal (mean of 19 months) cohort study. Sixty-seven obese children and adolescents (38 M, 29 F, age 6-16 (mean 11)y) who took part in a clinic-based weight control program. Percentage body fat was assessed at the start of the program by underwater weighing (UWW) and by bioelectrical impedance (BIA). Response to the program was assessed by a mathematical index (MI), based on observed and expected changes in height and weight, and by changes in percentage fat as measured by BIA. Adiposity, as assessed by BIA at the start of the program, was highly correlated to that obtained by UWW (r = 0.96 for fat-free mass). Changes in the MI over the program were correlated fairly well (r = -0.81, SEE = 3.57 kg) with changes in percentage fat as assessed by BIA. Using change in BIA as criterion, the MI is valid for assessing changes in percentage body fat of obese children and adolescents over time. This index is of use to clinicians who lack body composition equipment and need a quick method to analyze the effectiveness of a weight control program in obese children and adolescents.