Although empirical findings suggest no further rise in most European countries, overweight and obesity in childhood and adolescence still remain an urgent public health problem with a mean prevalence of about 20% (Inchley et al., 2016). According to the findings of the German KiGGS study, 15.4% of young people aged 3 to 17 suffer from overweight and another 5.9% are affected by obesity (Schienkiewitz et al., 2018a). Moreover, longitudinal findings show a high persistence of overweight over time, i.e. 64% of German children who were diagnosed as overweight remained overweight 11 years later (Schienkiewitz et al., 2018b). Given its negative effects on a wide range of health outcomes (physical and mental health, Daniels et al., 2015) but also on educational outcomes (Dadaczynski, Backhaus & Paulus, 2018) a number of interventions on health promotion and prevention have been developed and implemented in the school setting. These focus either on individual behavior or on contextual and environmental aspects of the school or - in line with the health promoting school approach - on both strategies. Against this backdrop, the current landscape of school-based interventions on overweight prevention is complex and difficult to overlook. Moreover, next to the amount of available interventions their conceptual orientation is largely unknown. Hence, the aim of the present paper is to present an overview of school-based interventions on overweight prevention and their conceptual characteristics. 

Funded by the Federal ministry of health, the so called SCAP project (Systematization of Conceptual Approaches) was carried out from June 2015 to December 2016 and aimed to: (1) develop a set of evidence-based criteria (criteria catalog) for the systematization of conceptual approaches of child and adolescent overweight, (2) identify German interventions on childhood and adolescence overweight prevention in kindergarten, schools, communities, and families, (3) systemize the conceptual approaches using the criteria catalog and to identify gaps, improvement potential, and recommendations for action. To develop a set of criteria, a systematic literature search was conducted in the field of health and overweight promotion/prevention across different settings (Babitsch et al., 2016). Using a priori defined inclusion and exclusion criteria interventions on overweight prevention were searched on German intervention databases (n=7). This step resulted in a total of n=435 interventions over all settings. The assessment of these interventions proved to be difficult because of a lack of information provided. Therefore, the qualitative assessment was extended by an online survey of all intervention providers that has been realized from April to June 2016. The online questionnaire comprised 22 questions about different facets of the interventions (e.g. setting, target groups, topics, methods and strategies, intervention delivery (intensity, dose), degree of participation and evaluation). After three postal and electronic reminders, the response rate was 41 percent (n = 185). Of these, 88 interventions account for the school setting. The focus of the presentation are the results of the online study on school-based interventions.

More than half of the 88 school-based interventions (59%) operate within the school setting alone, whereas 18% where implemented in two and 23% in three or four settings. Regarding the determinants of overweight, nutrition and physical activity were most commonly addressed, aspects on mental health issues only by 42% of all school-based interventions. While one-third only address one determinant, another third of the interventions consider three determinants at the same time. With regard to the methods (range: 1 to 8), more than three methods are used by each intervention on average (M=3.3). Educational techniques (e.g. teaching lesson) and informational materials are most commonly used, while activities on organizational development (27%) and structural development (13%) are much less common. According to the intervention providers, about three quarters of all interventions have a theoretical-conceptual foundation. However, when asked for specific theories and models a heterogeneous picture emerged. In addition to general theoretical perspectives (e.g. salutogenesis, socio-ecological model), some providers refer to guidelines or recommendations and only in a few cases very concrete intervention theories are mentioned. In terms of evaluation, 80% and 85% of the respondents indicate that a summative or a formative evaluation has been conducted for their intervention. With regard to the outcomes that have been evaluated, of a dominance of proximal and intermediate health outcomes (e.g. knowledge, attitudes, behavior) can be determined. Although the results are merely descriptive, heterogeneous intervention complexity can be seen. On the one hand, there are interventions that are implemented in different settings, address various determinants of overweight, and use different methods. On the opposite side of the continuum are rather simple and robust interventions focusing on the school, one specific determinant and are implemented using less methods. The combination of different characteristics to intervention types should be pursued in further analysis.

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