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

OBJECTIVE: To study the usefulness of a mathematical index for assessing ch anges in body composition of obese children and adolescents who undergo a w eight control program, DESIGN: A short-term longitudinal (mean of 19 months) cohort study. SUBJECTS: 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. MEASUREMENTS: 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 observe d and expected changes in height and weight, and by changes in percentage f at as measured by BIA. RESULTS: Adiposity, as assessed by BIA at the start of the program, was hig hly correlated to that obtained by UWW (r = 0.96 for fat-free mass). Change s 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. CONCLUSION: 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 an d need a quick method to analyze the effectiveness of a weight control prog ram in obese children and adolescents.