Between 2019 and 2021, 199 adolescents collaborated with adults in 15 participatory action research projects, called Youth Alliances, to contribute to system-directed obesity prevention in five EU countries. We investigated if and how these Youth Alliances included diverse youth, enhanced engagement, generated policy proposals and changed problem perception.

We assessed the Youth Alliances from a micro-sociological perspective of negotiated order and attended to what we call third order effects: that participatory action provides time and space to renegotiate meaning.

We used a case-comparative interpretive framework to attend to complexity. Based on collaborative and comparatively triangulated observations, documents and contextual data, we studied adaptations to Youth Alliances due to contextual demands and local contingencies in micro-interactions.

Youth Alliances led to the involvement of adolescents from diverse backgrounds who participated meaningfully in a form of partnership, generated a wide variety of policy proposals, and learned about obesogenic systems, policies and participation in the process.

A focus on meaning-making and interaction reveals how one participation approach can have multiple and even contradictory outcomes depending on non-linear, emergent and contingent local interactions. Some of the outcomes represent well-known second order effects (e.g., changing power relations). But we also point to what we call third order effects: specific activities generated time and space for social interactions in which novel meaning could arise and consolidate.