ABSTRACT
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.