Tackling obesity among adolescents requires the optimization of existing obesity treatment strategies. For this purpose, social and personal circumstances, individual needs and behavior of therapy participants need to be analyzed to tailor aims, content and methods of therapy interventions to the target groups. A total of 432 obesity therapy participants between 11 and 17 years completed a written survey in a national multi-center study conducted in 2015. The data collection on behavior, in terms of physical activity, media use and sociodemographic variables, was based on questionnaires from the KiGGS, HBSC and JIM studies. The results show that participants were found to be physically active together with friends (75.5%), alone (41.4%) and in sports clubs (34.9%). Girls (OR 1.55) were less likely to participate in sports clubs. Social networks, especially YouTube, WhatsApp, Instagram and Facebook, were widely used. However, differences emerged among sociodemographic groups (e.g., boys vs. girls) regarding the use of social network features. A third of participants reported that smartphone apps regularly encouraged them to exercise. The findings imply that obesity therapy approaches need to be adapted and more differentiated according to the specific needs of the target groups.

Objective: Loss of control (LOC) eating is a salient indicator of eating disorder psychopathology in adolescents and is associated with marked distress. While research has focused on the relevance of episode size, clinical significance of LOC eating frequency has rarely been explored. Therefore, this study aimed at identifying LOC eating prevalence with respect to its recurrence and associated variables in a community-based sample. Method: Participants were 1643 adolescents, aged 12-20 years (62.4% female). Based on EDE-Q self-report, participants were categorized as those reporting recurrent (N = 156; 9.5%), non-recurrent (N = 226; 13.8%) and no LOC eating (N = 1261; 76.7%). Results: Adolescents with recurrent LOC eating reported clinically relevant and significantly greater eating disorder psychopathology, functional impairment and distress because of LOC eating, and a significantly higher body mass index (BMI, kg/m2) than adolescents with non-recurrent and those without LOC eating. Discussion: These results underline that LOC eating is a common eating behavior among adolescents in the community associated with clinical characteristics of eating disorders, and could therefore be a risk factor for developing full- or partial-syndrome eating disorders. Further research on the classification of eating disorders in adolescents with LOC eating and severity indicators is warranted.

Background: Genome-wide association studies have identified variants within the FTO (fat mass and obesity associated) locus as the strongest predictors of obesity amongst all obesity-associated gene loci. Recent evidence suggests that variants in FTO directly affect human adipocyte function through targeting IRX3 and IRX5 and thermogenesis regulation. Aim: We addressed the relevance of this proposed FTO-IRX pathway in adipose tissue (AT) of children. Results: Expression of IRX3 was higher in adipocytes compared to SVF. We found increased adipocyte-specific expression of IRX3 and IRX5 with the presence of the FTO risk haplotype in lean children, whereas it was unaffected by risk variants in obese peers. We further show that IRX3 expression was elevated in isolated adipocytes and AT of lean compared to obese children, particularly in UCP1-negative adipocytes, and inversely correlated with BMI SDS. Independent of BMI, IRX3 expression in adipocytes was significantly related to adipocyte hypertrophy, and subsequent associations with AT inflammation and HOMA-IR in the children. Conclusion: One interpretation of our observation of FTO risk variants linked to IRX3 expression and adipocyte size restricted to lean children, along with the decreased IRX3 expression in obese compared to lean peers, may reflect a defense mechanism for protecting body-weight, which is pertinent for lean children.