School-Based Body Image Concerns Prevention

The investigators conducted a cluster randomized controlled trial with two assessment points (baseline, post-intervention and 8-week follow-up) comparing the "Digital Bodies" program to a no-intervention control group. To ensure that all students benefit from the intervention, the control group received the intervention after the 8 weeks.

Randomization was performed at the school level, not the student level. This is known as cluster randomization, and it aims to avoid "contamination effects" (Smolak & Levine, 2001).

The research protocol was approved by the GHC Institutional Review Board (Protocol No. 0025GHCIRB). Written informed consent was obtained from each participant and their parent(s) or legal guardian(s), authorizing the collection and anonymized use of data for research purposes.

Participants Four hundred and forty-nine eligible participants were recruited from December 2024 to May 2025. Secondary school administrators were approached either by phone or email and received an information letter describing the key elements of the prevention program. Participation required the school principal-or a designated representative-to provide written confirmation through a signed agreement. Eligible participants were students in their first or second year of upper secondary school who, along with their parents, provided written informed consent. Students who did not complete the baseline questionnaire and the case report form were excluded from the analysis but were still permitted to participate in the intervention itself.

The "Digital Bodies" Program and Study Implementation The Digital Bodies intervention, adapted from an English study that demonstrated its effectiveness (Bell et al., 2022), consists of a one-hour interactive session. The session begins with a brief self-affirmation exercise, in which participants are asked to describe something important to them and explain why. When used at the start of the intervention, this technique can help reduce participants' initial resistance to health-promotion messages.

The core of the intervention involves the use of cognitive dissonance techniques and the development of critical literacy skills to encourage adolescents to critically reflect on appearance ideals, as well as to foster the skills needed to challenge such ideals.

The content focuses on (i) the socially constructed nature of body ideals across time and culture, with particular attention to social media spaces, (ii) the deconstruction of myths surrounding the "perfect body" (e.g., image editing, idealization), again with a focus on social media environments, and (iii) the role of adolescents in creating, perpetuating, and reinforcing these ideals through digital technologies, including social media.

The session concludes with an implementation-intentions exercise, where participants develop specific behavioral plans describing how they would act in three situations in which appearance ideals are most salient, to challenge or resist them.

Inclusion criteria

• First or second year of upper secondary school

Exclusion criteria

• They and their parents did not provide written informed consent