No abstract

Background: Obesity and age influence reliability of dual energy X-ray absorptiometry scanning (DEXA) and bioimpedance spectroscopy (BIS). Both are used in clinical settings, but have not been compared for measurements in obese children. We compared DEXA and BIS for evaluating body composition and inherent changes in obese children before and after a 10-month weight loss program.Methods: DEXA and BIS were used to evaluate 130 patients at baseline and 75 at followup. We tested agreement between the two techniques using Bland-Altman plots and proportional bias using Passing-Bablok regressions. Results:The Bland-Altman plots showed wide agreement limits before and after weight loss when monitoring longitudinal changes. At baseline, the Passing-Bablok regressions revealed a proportional bias for all body compartments. After significant weight loss no proportional bias was found for fat mass and percentage, although BIS systematically underestimated fat mass by 2.9 kg. Longitudinally, no proportional bias was found in the measured changes of absolute fat, fat-free mass and fat-free percentage between both methods, although BIS systematically underestimated fat and fat-free mass by 2.6 kg and 0.7 kg, respectively. Conclusion:While BIS and DEXA are not interchangeable at baseline, the agreement between the two improved after significant weight loss. Proportional changes in fat mass, fatfree mass and fat-free percentage were similar for both techniques. BIS is a viable alternative to DEXA for future paediatric obesity studies measuring treatment effect at group levels, but is not superior to DEXA and cannot be used for monitoring individual changes due to wide limits of agreement.

BackgroundChildhood obesity has increased worldwide, becoming a significant public health concern. Brain-derived neurotrophic factor (BDNF) plays an important role in the central regulation of food intake and body weight, but little is known regarding its role in childhood obesity. Next to obesity, BDNF has been linked to obstructive sleep apnea (OSA) and endothelial dysfunction, two obesity-related comorbidities. The aim of this study is to investigate how BDNF, OSA and endothelial dysfunction interact in children with obesity and to determine the effect of weight loss on serum BDNF levels.MethodsChildren and adolescents with obesity aged 8–18 years who were enrolled in a multidisciplinary obesity treatment (MOT) in a tertiary hospital, were prospectively included. Several examinations were conducted during this MOT; at baseline, after 6 months and after 12 months, including the assessment of endothelial function, body composition measurements and a polysomnography. BDNF levels were measured on a serum sample by means of ELISA.ResultsA total of 103 patients with obesity was included, of which 20 had OSA (19.4%). BDNF levels were comparable in children with obesity and OSA and children with obesity but without OSA (26.75 vs. 27.87 ng/ml, p = 0.6). No correlations were found between BDNF and sleep-related variables or between BDNF and endothelial function parameters nor between BDNF and adiposity measures. To investigate if the interaction between OSA and endothelial dysfunction had an influence on BDNF levels, a general linear model was used. This model revealed that a diagnosis of OSA, as well as the interaction between OSA and maximal endothelial dilatation, contributed significantly (p = 0.03, p = 0.04, respectively) to BDNF levels. After 1 year of weight loss therapy, BDNF levels did not change (26.18 vs. 25.46 ng/ml, p = 0.7) in our population.ConclusionBDNF concentrations were comparable in children with obesity, both with and without OSA, indicating that BDNF levels are not affected by OSA. However, we did find an interaction effect of OSA and endothelial function on BDNF levels.

Background: Currently available treatment programs for children with obesity only have modest long-term results, which is (at least partially) due to the poorer self-control observed within this population. The present trial aimed to determine whether an online self-control training, training inhibition, and redirecting attentional bias, can improve the short- and long-term treatment outcome of (in- or outpatient) child obesity treatment programs.Methods: In this double-blind multi-center randomized controlled trial (RCT), participants aged 8–18 years with obesity were allocated in a 1:1 ratio to receive an online self-control or sham training added to their in- or outpatient multidisciplinary obesity treatment (MOT) program. The primary endpoint was BMI SDS. Data were analyzed by linear mixed models and the main interactions of interest were randomization by time and randomization by number of sessions, as the latter was cumulatively expressed and therefore represents the effect of increasing dose over time.Results: One hundred forty-four inpatient (mean age 14.3 ± 2.2 years, BMI 2.7 ± 0.4 SDS, 42% male) and 115 outpatient children (mean age 11.9 ± 2.1 years, BMI 2.4 ± 0.4 SDS, 45% male) were included. Children's BMI lowered significantly during treatment in both the in- and outpatient treatment centers, p < 0.001. In a mixed model with BMI as dependent variable, randomization by time was non-significant, but the number of self-control trainings (randomization * number of sessions) interacted significantly with setting and with age (p = 0.002 and p = 0.047), indicating a potential effect in younger inpatient residents. Indeed, a subgroup analysis on 22 inpatient children of 8–12 years found a benefit of the number of self-control trainings on BMI (p = 0.026).Conclusions: The present trial found no benefit of the self-control training in the entire study population, however a subgroup of young, inpatient participants potentially benefited.