Change in body fat during a family-based treatment of obesity in children: the relative importance of energy intake and physical activity.

OBJECTIVE The aim of the current study was to examine to what extent changes in reported energy intake and physical activity predict changes in body fat during a family-based outpatient treatment of obesity in children. METHODS Total body fat (DXA), reported energy intake (4-day diet record), and physical activity (accelerometer) was measured in 99 children (age 7-12 years, mean BMI SDS = 2.99) at baseline as well as after 6 months 2 years of treatment. Repeated measures (GLM), growth modeling, and structural equation modeling (SEM) were applied in the data analyses. RESULTS There was significant decrease in body fat, reported energy intake, and physical activity at both follow-ups (p < 0.001) compared to baseline. Changes in reported energy intake from baseline to 6 months predicted a decrease in body fat from baseline to 6 months (β = 0.68, p < 0.001). In addition, changes in reported energy intake had a strong indirect effect on body fat at 2-year follow-up, mediated by changes in body fat from baseline to 6 months (indirect β = 0.50, p < 0.001). Changes in physical activity did not predict changes in body fat during treatment. CONCLUSIONS Changes in reported energy intake significantly affected body fat at 6 months and indirectly predicted the amount of body fat at 2-year follow-up. The indirect effect was mediated by a decrease in body fat obtained during the first phase of treatment.