Search

Unlabelled: The prevalence of obesity in children has increased dramatically during the past decades, and requires efficient care., Objectives: To determine changes in anthropometric parameters and basal metabolic rate (BMR) in obese adolescents during and after 2 types of weight-reduction programs., Subjects and Methods: Twenty-six adolescents (group I, Z-score of BMI = 4.72) followed a 9-month-weight reduction program including a moderate energy restriction and regular physical activities in a specialized institution. In addition, 39 adolescents (group E, Z-score of BMI = 2.83) followed at home a 9-month-weight reduction program including medical and dietetic advices. Body composition (by impedancemetry) and BMR (by indirect calorimetry) were assessed before the beginning (M0), 4 months after (M4) and at the end (M9) of the programs, then 4 months (M13) and 16 month (M25) after the end of the weight-reduction programs., Results: Twenty-two adolescents in group I and 20 adolescents in group E completed the study. At M0, age, body weight (BW), fat-free mass (FFM) and BMR of subjects of group I were higher (1.0 year, 36 %, 30 % and 23 %, respectively, P < 0.001), than those of group E. Pubertal stage and percentage of fat mass (FM) were not significantly different between the 2 groups. At M9, adolescents of group I showed significant reductions in BW and FM (-19 and -37 %, respectively, P < 0.001), but not significant differences in FFM. In addition, BMR decreased significantly between M0 and M4, both in absolute value (-6.7%, P < 0.001) and after adjustment for FFM (-5.8%, P < 0.001), and the difference was maintained until M9. Between M9 and M13, BW and Z-score of BMI were maintained in 12 adolescents, but increased (+9.7% and 14.8%, respectively, P < 0.001) in 10 adolescents. However, BMR did not change significantly in all adolescents. Between M13 and M25, BW, FM, FFM and BMR increased significantly (+13%, +34%, +6% et +5%, respectively, P < 0.001). During the 25 month period, adolescents of group E showed significant increases in BW, FFM and BMR (+8%, +14% and +10%, respectively, P < 0.001), and maintained their Z-score and FM., Conclusion: The reduction in BMR during the weight-reduction program at the institution could contribute to body weight regain in the post-obese adolescents if they do not maintain the lifestyle habits taught during the weight-reduction period. In other respects, Z-score was stabilized in 51% of domiciled obese adolescents.

Context: Professionals in charge of overweight and obese children and adolescents need a simple, reliable and precise method for assessing body composition., Objectives: To compare body composition as assessed by dual-energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA) and the skinfold thickness (SFT) method in overweight and obese adolescents, and to establish and validate new predictive equations of body composition from BIA measurements using DXA as standard method., Subjects and Methods: Body composition was assessed in 143 obese adolescents (Z-score = 3.2 +/- 1.4) aged 12 to 17 years by DXA, BIA (RJL System, Analycor and Analycor XF models) and SFT (Siri and Slaughter's equations). New prediction equations of fat mass (FM) as assessed by DXA were computed from BIA measurements in a calibration group, and validated in an homologous group of subjects. Results. - The Bland-Altman test showed that compared to DXA, BIA underestimated FM by 2.8 +/- 2.0 kg and 2.3 +/- 2.1 kg using the RJL System and Analycor impedancemeter, respectively (P < 0.001). With the Analycor XF model, FM was underestimated by 3.3 +/-2.6 kg in boys, and over-valued by 0.6 +/- 2.4 kg in girls. On the contrary, the predictive equation of Wabitsch et al. overvalued FM by 6.2 +/- 2.9 kg. The SFT method overvalued FM by 2.1 +/- 5.0 kg in boys and underestimated FM by 2.3 +/- 3.5 kg in girls using Slaughter et al. equation, while Siri's equation underestimated FM by 4.0 +/- 2.9 kg (P < 0.001). The alternative to the DXA method to assess FM was BIA with new prediction equations including gender, body weight, height(2)/resistance and reactance., Conclusion: DXA, BIA and the SFT method were not directly interchangeable. The SFT method was inadequate to assess body composition in overweight and obese adolescents. BIA and new prediction equations could be an alternative to the DXA method in overweight and obese adolescents.

Objectives: To develop a simple, rapid, and unbiased test to assess usual physical activity in overweight adolescents during a routine medical consultation., Methods: Adolescents were selected. Their heart rate (HR) and blood pressure (BP) were measured at rest and when standing, before the beginning of the test. Subjects went up and down a 2-step apparatus during 4 minutes at a rate of 92 steps/min. HR was monitored. At the end of the test, the HR was noted and BP measured immediately. The effects of usual physical activity and gender on HR and BP were tested by ANOVA. In addition, an activity questionnaire was filled in by 43 subjects over 7 days and given to the doctor who completed the information during the visit and assessed usual physical activity., Results: 56 adolescents of both sexes, aged 10-17 years (31 sedentary [S] overweight, and 25 active [A] post-obese subjects) underwent a step-test. The increase in HR during the test was significantly higher in S than in A subjects (66.2 +/- 2.3 vs 52.3 +/- 2.5 bpm, p < 0.001). However, the variations in BP did not supply reliable assessment of usual physical activity. The activity questionnaire had been filled in satisfactorily by 72% of subjects. In 95% of cases, the classification of subjects as S or A by the step-test agreed with the classification based on the questionnaire., Conclusion: The step-test provided the rapid and reliable assessment of usual physical activity of the children (from 6-7 years of age) in 95% of cases during a routine consultation (30 min), and the activity questionnaire enabled the doctor to check the conclusions of the step-test and recommend to the parents physical activities adapted to the physical capacities of their children.