Analyse longitudinale des variations de la composition corporelle et du métabolisme de base d'adolescents obèses pris en charge en institution ou à domicile

Abstract

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.