Purpose: Impact of lifestyle modification on obesity control during adolescence, a period of significant physical growth and development, is less quantitatively evaluated. Therefore, we investigated the impact of changes in reported energy intake and physical activity on anthropometrics and body composition in adolescents.
Methods: Participants were obese adolescents aged 11-18 years. All of them have a body mass index (BMI) ≥ 95th percentile specific for age and gender according to the 2000 CDC Growth Charts. The intervention consists of supervised physical activity, structured nutrition education and dietary modification, and behavioral support in 6 months. Hundred and forty-five obese adolescents completed the study.
Results: Compared to baseline, significant reductions in body weight (-1.4 kg, p < 0.001) and BMI (-0.1 kg/m(2), p < 0.001) were observed at 6 months. When compared to expected growth trajectories on the 2000 CDC Growth Charts, body weight and BMI were reduced by 3.6 kg and 1.5 kg/m(2), respectively, in boys and 5.6 kg and 1.9 kg/m(2) in girls. Age was inversely associated with changes in weight (β = -1.48 kg, p < 0.01) and BMI (β = -0.32 kg/m(2), p = 0.03). There was a dose-response relationship between reduction in energy intake and weight loss. A decrease of 100 kcal/day was significantly associated with reductions in body weight 0.30 kg, BMI 0.09 kg/m(2), and BMI Z score 0.01 (all p < 0.01). Physical activity was not significantly associated with changes in anthropometrics or body composition.
Conclusions: Reduction in energy intake was a significant predictor of obesity reduction in these adolescents. A quantitative evaluation of adolescent weight loss programs should account for natural growth and development.