Implementation and effectiveness of a school-based intervention to increase adherence to national school meal guidelines: a non-randomised controlled trial.

OBJECTIVE: Implementation of school meal guidelines is often inadequate, and evidence for effective implementation strategies for school-based nutrition interventions is limited. The aim of the present study was to examine the implementation and effectiveness of a multi-strategy implementation intervention to increase adherence to the Norwegian national school meal guideline. DESIGN: The study was a school-based hybrid implementation effectiveness trial with a pre-post non-equivalent control group design, testing three implementation strategies: internal facilitation, training and an educational meeting. SETTING: Primary schools and after-school services in two counties in south-east Norway. PARTICIPANTS: School principals, after-school leaders and class teachers from thirty-three schools in the intervention county and principals and after-school leaders from thirty-four schools in a comparison county. RESULTS: There was a significant difference of 4 percentage points in change scores between the intervention and the comparison groups at follow-up, after adjusting for baseline adherence (B = 0·04, seB = 0·01, t = 3·10, P = 0·003). The intervention effect was not associated with the school's socio-economic profile. School-level fidelity was the implementation dimension that was most strongly correlated (r s = 0·48) with the change scores in the intervention group, indicating that principals' support is important for gaining the largest intervention effects. CONCLUSIONS: A school-based intervention with low intensity, based on trained teachers as internal facilitators, can increase adherence to the national school meal guideline among Norwegian primary schools, irrespective of local socio-economic conditions. Implementation fidelity, at an organisational level, may be a useful predictor for intervention outcomes in schools.

Mediators and moderators of the effects of a school-based intervention on adolescents' fruit and vegetable consumption: the HEIA study.

OBJECTIVE: To examine whether targeted determinants mediated the effects of the HEalth In Adolescents (HEIA) intervention on fruit and vegetable (FV) consumption and explore if these mediating effects were moderated by sex, parental education or weight status. DESIGN: Cluster-randomised controlled trial. SETTING: The HEIA study (2007-2009) was a Norwegian 20-month multi-component school-based intervention to promote healthy weight development. FV consumption and targeted determinants were self-reported at baseline, mid-way (8 months) and post-intervention (20 months). PARTICIPANTS: Adolescents (11-13-year-old) in twenty-five control schools (n 746) and twelve intervention schools (n 375). RESULTS: At post-intervention, more adolescents in the intervention group compared with the control group had knowledge of the FV recommendations (OR: 1·4, 95 % CI 1·1, 1·9) and reported a decreased availability of vegetables at home (ß: -0·1, 95 % CI -0·2, 0·0). Availability/accessibility of FV at home, availability of vegetables at dinner, taste preferences for different types of FV and knowledge of the FV recommendations were positively associated with the consumption of FV. However, none of the post-intervention determinants significantly mediated the intervention effects on FV consumption. Although no moderating influences by sex, parental education or weights status were observed on the mediating effects, exploratory analyses revealed significant moderations in the b-paths. CONCLUSIONS: Since none of the targeted determinants could explain the increase in FV consumption, it remains unclear why the intervention was effective. Reporting on a wide range of mediators and moderators in school-based interventions is needed to reveal the pathways through which intervention effects are achieved.

Learning from the CO-CREATE project: A protocol for systems thinking across research (STAR).

The CO-CREATE project aimed to work with young people to create, inform, and disseminate obesity-preventive evidence-based policies using a complex systems perspective. This paper draws lessons from this experience and proposes a protocol for embedding systems thinking within a research project. We first draw on existing systems thinking frameworks to analyze how systems thinking was translated across CO-CREATE, including the flow and relationship between the work packages and in the methods used. We then take the lessons from CO-CREATE and the principles of existing systems thinking frameworks-which focus on various points of intervention planning and delivery but not on research projects as a whole-to formulate a protocol for embedding systems thinking across a research project. Key lessons for future planning and delivery of systems-oriented research projects include incorporating "boundary critique" by capturing key stakeholder (adolescent) values and concerns; working to avoid social exclusion; ensuring methodological pluralism to allow for reflection and responsiveness (with methods ranging from group model building, Photovoice, and small group engagement); getting policy recipients to shape key questions by understanding their views on the critical drivers of obesity early on in the project; and providing opportunity for intraproject reflection along the way.

Co-creating obesity prevention policies with youth: Policy ideas generated through the CO-CREATE project.

Despite growing recognition of the importance of applying a systems lens to action on obesity, there has only been limited analysis of the extent to which this lens has actually been applied. The CO-CREATE project used a youth-led participatory action research approach to generate policy ideas towards the reduction of adolescent overweight and obesity across Europe. In order to assess the extent to which these youth-generated policy ideas take a systems approach, we analyzed them using the Intervention Level Framework (ILF). The ILF ascribes actions to one of five system levels, from Structural Elements, the least engaged with system change, up to Paradigm, which is the system's deepest held beliefs and thus the most difficult level at which to intervene. Of the 106 policy ideas generated by young people during the CO-CREATE project, 91 (86%) were categorized at the level of Structural Elements. This emphasis on operational rather than systems level responses echoes findings from a previous study on obesity strategies. Analyzing the distribution of systems level responses using the ILF has the potential to support more effective action on obesity by allowing identification of opportunities to strengthen systems level responses overall.

Designing a youth-led Dialogue Forum tool: The CO-CREATE experience.

While obesity prevention represents an established field of research, the inclusion of young people, who are regularly cited as an important priority group, are rarely actioned in long-term studies. This paper focuses on the development of a dialogue tool intended to tackle this issue, engaging, and eliciting insights on the theme of obesity prevention, by young people and for young people. As part of the CO-CREATE project, this tool was co-developed by designers, public health, and youth participation experts, researchers, and young people. Co-creation is a key methodology in the design of the dialogue tool, as young people were involved in all stages of the development process. This paper elaborates on the process of co-designing a dialogue tool that helps explore obesity prevention policy ideas from multiple perspectives, and describes the design principles that informed the process and the final versions of the tool. The purpose of the Dialogue Forum tool is for youth to engage policymakers and other relevant stakeholders to discuss and refine co-created and youth-initiated ideas for healthier food and physical activity environments. We analyze how specific design principles were integrated into different prototypes and the value of this within the project and the field.

Adolescents' capacity to take action on obesity: A concurrent controlled before-and-after study of the European CO-CREATE project.

This study evaluated the effect on reported readiness for action and attitudes toward obesity prevention among older adolescents (mean age 17) who took part in a youth-led participatory action research European initiative (CO-CREATE Youth Alliances) compared with a comparison group that acted as controls. This was a concurrent before-and-after controlled study across five countries and took place between September 2019 and October 2020. Adolescents (n = 159) recruited from schools and youth organizations came together with researchers and formed 15 Youth Alliances. An online questionnaire measuring their readiness for action and attitudes toward obesity prevention was administered. Alliance members (n = 62) who filled in the questionnaire at both baseline and postinitiative, and adolescents from the comparison group (n = 132) who completed the questionnaire twice were included in the main analysis. Two-level linear mixed models controlling for country-related variance were fitted. Alliance members scored significantly higher than the comparison group on two factors in each of the readiness for action, responsibility, and drivers of behavior concepts. The findings suggest that involving youth in co-creating policies to prevent obesity may increase adolescents' readiness for action and promote a shift in adolescents' conceptualization of obesity from an individual perspective to a societal responsibility and drivers of behavior.

System dynamics simulation models on overweight and obesity in children and adolescents: A systematic review.

It has increasingly been recognized that developing successful obesity prevention policies and interventions requires understanding of the complex mechanisms driving the obesity pandemic and that models could be useful tools for simulating policies. This paper reviews system dynamics simulation models of mechanisms driving childhood overweight and obesity and/or testing of preventive interventions. A systematic literature search was conducted in six databases from inception to January 2023 using terms related to overweight/obesity, children, and system dynamics. Study descriptives, mechanisms, and where to intervene (the leverage points), as well as quality assessments of the simulation models were extracted by two researchers into a predetermined template and narratively synthesized. Seventeen papers describing 15 models were included. Models describing the mechanisms ranged from only intrapersonal factors to models cutting across multiple levels of the ecological model, but mechanisms across levels were lacking. The majority of interventions tested in the simulation models were changes to existing model parameters with less emphasis on models that alter system structure. In conclusion, existing models included mechanisms driving youth obesity at multiple levels of the ecological model. This is useful for developing an integrated simulation model combining mechanisms at multiple levels and allowing for testing fundamental system changes.

What policies are there and what policies are missing? A Photovoice study of adolescents' perspectives on obesity-prevention policies in their local environment.

The aim of this study was to investigate adolescents' critical awareness of whether obesity prevention policies targeting physical activity (PA) and nutrition were operating in their local community. Participants were 41 adolescents (aged 16-18, 90% women) recruited from three communities in Poland. Prior to this study, they were involved in obesity-prevention participatory initiatives (conducted within the CO-CREATE project), where obesity-related public policy limitations were analyzed in a youth-led discussion. A Photovoice exercise was designed to capture obesity-related public policies that were either present or absent in young people's local environments. The photographs (N = 213) were coded and mapped according to the policy themes they illustrated, using the MOVING and NOURISHING frameworks. The public policies represented in the photographs are most frequently related to: healthy retail or food service environments; food advertising or promotion; structures and surroundings that promote PA; and infrastructure and opportunities that support public or active transport. Adolescents are critically aware of the presence and lack of specific public policies operating in their local environment, particularly policies affecting structural aspects of food and PA environments. Policy-oriented photovoice exercises may prompt critical awareness among adolescents and empower them to contribute to obesity prevention policy processes.

Understanding the dynamics emerging from the interplay among poor mental wellbeing, energy balance-related behaviors, and obesity prevalence in adolescents: A simulation-based study.

Both obesity and poor mental wellbeing have a high prevalence in European youth. Adolescents in six countries identified mental wellbeing factors as main drivers of youth obesity through systems mapping. This study sought to (1) explore the dynamics of the interplay between poor mental wellbeing, energy balance-related behaviors, and adolescent overweight and obesity prevalence and (2) test the effect of intervention point scenarios to reduce adolescent obesity. Drawing on the youth-generated systems maps and a literature synthesis, we built a simulation model that represents the links from major feedback pathways for poor mental wellbeing to changes in dietary, physical activity, and sleep behaviors. The model was calibrated using survey data from Norway, expert input, and literature and shows a good fit between simulated behavior and available statistical data. The simulations indicate that adolescent mental wellbeing is harmed by socio-cultural pressures and stressors, which trigger reinforcing feedback mechanisms related to emotional/binge eating, lack of motivation to engage in physical activity, and sleep difficulty. Targeting a combination of intervention points that support a 25% reduction of pressure on body image and psychosocial stress showed potentially favorable effects on mental wellbeing-doubling on average for boys and girls and decreasing obesity prevalence by over 4%.

Encouraging greater empowerment for adolescents in consent procedures in social science research and policy projects.

The United Nations Convention on the Rights of the Child emphasizes the importance of allowing children and adolescents to influence decisions that are important to them following their age and maturity. This paper explores the principles, practices, and implications around using parental versus child/adolescent consent when participating in social science research and policy development. Experiences from two studies are presented: The Confronting Obesity: Co-creating policy with youth (CO-CREATE) and the Health Behaviour in School-aged Children (HBSC) study, a World Health Organization (WHO) Collaborative Cross-National study. Although parental consent may be an important gatekeeper for protecting children and adolescents from potentially harmful research participation, it may also be considered an obstacle to the empowerment of children and adolescents in case they want to share their views and experiences directly. This paper argues that evaluation of possible harm should be left to ethics committees and that, if no harm related to the research participation processes is identified and the project has a clear perspective on collaborating with the target group, adolescents from the age of 12 years should be granted the legal capacity to give consent to participate in the research project. Collaboration with adolescents in the development of the research project is encouraged.

Longitudinal relationship between adolescents' mental health, energy balance-related behavior, and anthropometric changes.

Energy balance-related behaviors (EBRBs) are considered the immediate causes of adolescents' body weight increases, but adolescents have identified mental health as a contributor. Cross-sectional studies have reported associations between adolescents' mental health and obesity, but causal relationships and the role of EBRBs within this can only be established using longitudinal studies. This systematic review summarizes the findings of longitudinal studies investigating this relationship, in addition to the role of EBRB in the relationship. Multiple electronic databases were searched for longitudinal studies using keywords related to the adolescent population, mental health, EBRB, and body weight. In total, 1216 references were identified and screened based on previously defined eligibility criteria. Sixteen articles met the inclusion criteria. Most studies indicated that mental health-related measures like depression, anxiety, and body dissatisfaction were related to an increase in body weight later. As this review is focused on behavioral mediators, six studies reported associations between mental health-anthropometry dyad and EBRBs such as eating habits, screen time, physical activity, and sleep-as well as stressors like peer victimization. Future studies may focus on streamlining mental health measures and body weight outcomes to assess this relationship. Furthermore, more longitudinal investigations are needed to provide insight into the role of EBRBs in the mental health-body weight relationship during adolescence.

Mediators of parental educational differences in the intake of carbonated sugar-sweetened soft drinks among adolescents, and the moderating role of neighbourhood income.

BACKGROUND: Existing evidence suggests that the intake of sugar-sweetened beverages (SSB) among adolescents remains a public health concern and that socioeconomic differences in intake exist. Tackling these challenges requires identifying the factors associated with SSB intake and the mediators of socioeconomic differences in SSB intake among adolescents. Thus, this study aimed to explore (i) factors at different levels of the ecological model associated with the intake of carbonated soft drinks with added sugar (hereafter called soft drinks), (ii) mediators of the association between parental education and the intake of soft drinks(iii) whether neighbourhood income moderates the indirect effect of parental education on adolescents' soft drink intake through potential mediators. METHODS: Data from 826 7th graders in Oslo, Norway, who participated in the TACKLE cross-sectional study conducted in 2020 were used. The association between factors at the individual, interpersonal and neighbourhood food environment levels and the intake of soft drinks among adolescents was assessed, as well as the mediating roles of these factors for the differences in intake by parental education, using multiple logistic regression and mediation analysis, respectively. Moderated mediation analyses were used to explore whether an indirect effect of parental education on adolescents' soft drink intake through potential mediators varies across neighbourhood income areas. RESULTS: Higher perceived accessibility of SSB at home, increased parental modelling for SSB intake, and increased frequency of food/drink purchased from the neighbourhood store were associated with a higher intake of soft drinks among adolescents and mediated the differences in intake by parental education. Neighbourhood food environment factors were neither statistically significantly associated with adolescents' higher intake of soft drinks nor explained the differences in intake by parental education. Moderated mediation analysis showed that the mediating effect of perceived accessibility of SSB at home on the association between parental education and adolescent soft drink intake was stronger among those living in low neighbourhood income. CONCLUSIONS: Our study identified modifiable factors at the intrapersonal level (perceived accessibility of SSB at home and frequency of food/drink purchased from neighbourhood shops) and interpersonal levels (parental modelling for SSB intake) associated with a higher intake of soft drinks among adolescents and mediated the differences in the intake by parental education. The modifiable factors identified in this study could be targeted in public health initiatives among adolescents aimed at reducing the intake of soft drinks and the related differences by parental education.

Barriers and facilitators to implementation of nutrition-related actions in school settings in low- and middle-income countries (LMICs): a qualitative systematic review using the Consolidated Framework for Implementation Research (CFIR).

BACKGROUND: Low- and middle-income countries (LMICs) are particularly vulnerable to the double burden of malnutrition: co-existence of underweight, overweight, obesity, and/or diet-related non-communicable diseases. Nutrition-related double-duty actions in school settings have been identified as one of the ways to address this challenge. However, to be able to take full advantage of the potential impact, it is important to understand their implementation as well. The aim of this paper is to systematically review qualitative research on barriers and facilitators to the implementation of nutrition-related actions in the school settings in LMICs. METHODS: The following databases were searched: EMBASE, ERIC, MEDLINE, Global Health and PsycInfo (all on Ovid), Scopus (Elsevier), the Web of Science Social Sciences Citation Index, and Global Index Medicus from the World Health Organization. Of the 4253 identified records, 4030 were excluded after the abstract and title screen, leaving 223 for the full-text screen. A final 36 papers were included in this review. The consolidated framework for implementation research (CFIR) was used in the analysis. RESULTS: We identified barriers and facilitators to implementation linked to the following CFIR constructs/sub-constructs: design quality and packaging, cost (intervention characteristics); target group needs and resources, cosmopolitanism, external policy and incentives (outer setting); structural characteristics, readiness for implementation (inner setting); knowledge and beliefs (characteristics of individuals) and engaging, executing (process). All identified constructs apart from target group needs and resources, knowledge and beliefs, and engaging were predominantly barriers. Available resources were the most prevalent barriers across studies. CONCLUSION: This review identified barriers and facilitators to the implementation of nutrition-related actions based on qualitative articles in the school setting in LMICs, using the CFIR. Schools face continuous challenges in regard to funding and the government sector may have a role to play not only by offering financial assistance, but also through policy-making that would support healthy eating practices on school grounds. REGISTRATION: PROSPERO ID: CRD42022296159.

Good practice recommendations on implementation evaluation for policies targeting diet, physical activity, and sedentary behaviour.

Health policies aim to achieve specific health goals through system-level changes, unlike common health interventions that focus on promoting specific health behaviors on individual level. However, reliable data on the feasibility and implementation of policy actions across Europe are lacking. Moreover, no practice-oriented guidance exists for policy makers and implementers on how to evaluate policy implementation.As part of the Policy Evaluation Network, we aimed to synthesise knowledge on how to evaluate the implementation of policies promoting healthy diets, physical activity, and reducing sedentary behaviours. The multidisciplinary working group comprised 16 researchers and conducted two scoping reviews, three systematic reviews, two meta-reviews, two qualitative case studies and one quantitative case study over three years. The target populations included the general population, those at risk for obesity, and school children. Based on these reviews and case studies, this article summarises and presents the findings and lessons learned regarding the implementation evaluation of policies in nine case reports.Drawing on these experiences, three critical requirements for policy implementation evaluation were set: 1) conduct a comprehensive policy implementation evaluation from a multi-level perspective, 2) use implementation frameworks to address processes, determinants, and outcomes, and 3) engage relevant stakeholders in policy implementation evaluation. Finally, the consensus process resulted in 10 steps for the implementation evaluation of policies to promote physical activity and a healthy diet and to reduce sedentary behaviours, which adhere to the requirements and resources of the targeted policy.The findings of an implementation evaluation can lead to a better understanding of why policies work or not and can serve as a basis for developing solutions. This practice-oriented guidance outlines factors that should be considered in policy implementation evaluation to address its complexity. In this way, involved researchers and practitioners are empowered to engage in the evaluation process to close the knowledge gap regarding policy implementation.

Neighborhood deprivation, built environment, and overweight in adolescents in the city of Oslo.

BACKGROUND: Even though the social and built environment characteristics of neighborhoods have been studied as potential determinants of social inequalities in obesity among adults, fewer studies have focused on children. Our first aim was to investigate whether there were differences in the food and physical activity environments between different neighborhood deprivation levels in the city of Oslo. We also explored whether there was an association between the prevalence of overweight (including obesity) among adolescents and (i) neighborhood deprivation levels and (ii) food and physical activity environments of the neighborhoods they live in. METHODS: We conducted a food and physical activity environment mapping (using ArcGIS Pro) in all neighborhoods of Oslo, which were defined by administrative boundaries (sub-districts). The neighborhood deprivation score was calculated based on the percentage of households living in poverty, unemployment in the neighborhood, and residents with low education. A cross-sectional study including 802 seventh graders from 28 primary schools in Oslo residing in 75 out of 97 sub-districts in Oslo was also performed. MANCOVA and partial correlations were ran to compare the built environment distribution between different neighborhood deprivation levels, and multilevel logistic regression analyses were used to explore the effect of neighborhood deprivation and the food and physical activity environments on childhood overweight. RESULTS: We found that deprived neighborhoods had greater availability of fast food restaurants and fewer indoor recreational facilities compared to low-deprived neighborhoods. Additionally, we observed that the residential neighborhoods of the adolescents with overweight had greater availability of grocery and convenience stores when compared to the residential neighborhoods of the adolescents without overweight. Adolescents living in neighborhoods with high deprivation had a two-fold higher odds (95% CI = 1.1-3.8) to have overweight compared to adolescents living in neighborhoods with low deprivation, regardless of participants' ethnicity and parental education. However, the built environment did not determine the relationship between neighborhood deprivation and overweight in adolescents. CONCLUSION: The neighborhoods in Oslo with higher deprivation levels had more obesogenic characteristics than the low-deprived neighborhoods. Adolescents living in high-deprived neighborhoods were more likely to have overweight than their counterparts from low-deprived neighborhoods. Thus, preventive measures targeting adolescents from high-deprived neighborhoods should be put in place in order to reduce incidence of overweight.

Barriers and facilitators to the adoption of physical activity policies in elementary schools from the perspective of principals: An application of the consolidated framework for implementation research-A cross-sectional study.

Background: Studies have shown that policies to promote physical activity in schools can have a positive impact on children's physical activity behavior. However, a large research gap exists as to what determinants may influence the adoption of such policies. Applying the Consolidated Framework for Implementation Research (CFIR), we investigated barriers and facilitators to the adoption of physical activity policies in elementary schools in Baden-Wuerttemberg, Germany, from the perspective of school principals. Methods: A cross-sectional study was conducted between May and June 2021. School principals from elementary and special needs schools (n = 2,838) were invited to participate in the study. The online questionnaire used was developed based on the CFIR and included questions on school characteristics and constructs of the CFIR domains inner setting, characteristics of individuals, and process. Logistic regression analyses were performed to examine associations between policy adoption and school characteristics as well as CFIR determinants. Results: In total, 121 schools (4%) participated in the survey, of which 49 (40.5%) reported having adopted a policy to promote physical activity. Positive associations with policy adoption were found for general willingness among teaching staff [odds ratio (OR): 5.37, 95% confidence interval (CI): 1.92-15.05], available resources (OR: 2.15, 95% CI: 1.18-3.91), access to knowledge and information (OR: 2.11, 95% CI: 1.09-4.09), and stakeholder engagement (OR: 3.47, 95% CI: 1.24-9.75). Conclusions: This study provides a first insight into potential barriers and facilitators at the organizational level of schools that may be relevant to the adoption of physical activity policies, from the perspective of school principals. However, due to a low response rate, the results must be interpreted with caution. A strength of this study includes theoretical foundation through the use of the CFIR. The CFIR could be well-adapted to the school setting and provided valuable support for developing the questionnaire and interpreting the study results.

Overweight and obesity prevention for and with adolescents: The "Confronting obesity: Co-creating policy with youth" (CO-CREATE) project.

The CO-CREATE project focuses on the need for research on obesity prevention in adolescents to move away from studies of single interventions, toward the investigation of systems-based research incorporating youth involvement. This paper provides an overview of the project, presenting the objectives, design, and novel methodologies applied, as well as findings to date and anticipated outcomes. Adolescents (16-18 years old) in five European countries participated. Methods applied in the project include monitoring and benchmarking of policies, systematic literature reviews, epidemiological surveillance, linking observed overweight and obesity trends to observed policy landscapes, group model building to identify perceived drivers of obesity, alliance building with adolescents, dialog with stakeholders, and system dynamics modelling to explore the potential impact of policy options. Outcomes include tools for developing policy ideas and investigation of prevention strategies with adolescents, including policy databases, system maps of drivers of obesity, protocols for organizing youth alliances, an intergenerational policy dialog tool, and system dynamic models exploring the impacts of cocreated policy ideas. These outcomes make an important contribution to building a pan-European infrastructure for designing and evaluating policies and for providing youth with the opportunity to make their voices heard in the development and implementation of obesity prevention measures.

Recruiting and engaging adolescents in creating overweight and obesity prevention policies: The CO-CREATE project.

The CO-CREATE project aims to collaborate with adolescents across Europe in developing policy ideas that contribute to overweight and obesity prevention. In this paper, we present the theoretical basis and methodological approach to recruitment and engagement in the project. The principles of youth-led participatory action research were employed to design Youth Alliances in which adolescents and adults could collaborate. These Alliances should serve to promote and support adolescent participation and to develop policy ideas that would contribute to obesity prevention. Alliance members were recruited in two local geographical areas per country with a focus on reaching out to underrepresented youth. We started with fieldwork to assess locally relevant forms of inclusion and exclusion. The methodology entailed a handbook combining existing tools which could be used flexibly, a collaborative organization, and budgets for the alliances. Engagement started in local organizations, that is, schools and scouts, and with peers. Health- and overweight-related challenges were addressed in their immediate surroundings and supported the inclusion of experiential knowledge. Adolescents were then supported to address the wider obesogenic system when designing policy ideas. The CO-CREATE Alliances provide a concrete example of how to engage youth in public health, in a manner that strives to be participatory, transformative, and inquiry based.

Ethical considerations in engaging young people in European obesity prevention research: The CO-CREATE experience.

Engaging youth in obesity prevention research and policy action is essential to develop strategies that are relevant and sensitive to their needs. Research with young people requires critical reflection to safeguard their rights, dignity, and well-being. The CO-CREATE project used various methods to engage approximately 300 European youth aged 15-19 years in the development of policies to prevent adolescent obesity. This paper discusses ethical considerations made in the project pertaining to the youth's voluntary participation, their protection from obesity stigma, respect for their time, data privacy and confidentiality, power balance, and equality of opportunity to participate in the research. We describe measures implemented to prevent or limit the emergence of ethical challenges in our interaction with youth and discuss their relevance based on our experience with implementation. While some challenges seemingly were prevented, others arose related to the youth's voluntary participation, time burdens on them, and the sustainability of participation under the Covid-19 pandemic. Concrete and ongoing ethical guidance may be useful in projects aiming to interact and build collaborative relationships with youth for long periods of time.

Assessing policies to reduce adolescent overweight and obesity: Insights from a system dynamics model using data from the Health Behavior in School-Aged Children study.

Adolescent overweight and obesity (AdOWOB) in Europe has proven to be a persistent and complex problem, and appropriate systems methods may help in evaluating potential policy options. This paper describes the development of a system dynamics model of AdOWOB as part of the EU-funded CO-CREATE project. The model was developed using literature and data from the Health Behavior in School-Aged Children (HBSC) study across 31 European countries. We identified 10 HBSC variables that were included as direct or indirect drivers of AdOWOB in the dynamic model, seven at the level of the individual, and three related to the social environment. The model was calibrated to 24 separate cases based on four gender and perceived wealth segments for each of the five CO-CREATE countries (The Netherlands, Norway, Poland, Portugal, and the UK) and for Europe overall. Out of 10 possible intervention points tested, exercise, fruit, life dissatisfaction, school pressure, and skipping breakfast were identified as the top five most influential ones across the 24 cases. These model-based priorities can be compared with the policy ideas suggested by the CO-CREATE adolescents.