The aim of this study is to evaluate the feasibility and preliminary effects of PrevED MR, a group-based preventive intervention for adolescents and young adults at risk of developing eating disorders. PrevED MR is based on dialectical behavior therapy skills and uses mixed reality and virtual reality activities to support emotion regulation, mindfulness, distress tolerance, and body-related acceptance.

Participants will be randomly assigned to either the PrevED MR intervention group or a waiting-list control group. The intervention will be delivered over 6 weeks, with two sessions per week, for a total of 12 sessions. Assessments will be conducted at baseline and after the intervention to examine changes in eating disorder symptoms, body image acceptance, emotion regulation strategies, rumination, usability, sense of presence, cybersickness, satisfaction, and adherence.

Eating disorders are serious mental health conditions that often emerge during adolescence and young adulthood. Difficulties in emotion regulation, including rumination, emotional suppression, low emotional acceptance, and limited cognitive flexibility, are relevant processes associated with eating disorder risk and symptom maintenance. Preventive interventions that target emotion regulation skills may help reduce eating disorder risk in young people.

PrevED MR is a mixed reality- and virtual reality-supported preventive intervention designed for adolescents and young adults at risk of developing eating disorders. The intervention is grounded in dialectical behavior therapy skills training and combines psychoeducation, paper-based exercises, group activities, and guided immersive experiences. The program focuses on core skills related to mindfulness, emotion identification, emotion regulation, distress tolerance, acceptance, and non-judgmental body-related exposure.

This study is a pilot randomized controlled trial with two parallel arms: an experimental intervention group and a waiting-list control group. Participants allocated to the experimental group will receive the PrevED MR intervention over 6 weeks, with two sessions per week, for a total of 12 sessions. Sessions will be delivered face-to-face in small groups and supervised by trained mental health professionals. Participants allocated to the waiting-list control group will continue their usual activities during the initial study period and will not receive the intervention before the post-intervention assessment.

The study will recruit Spanish-speaking adolescents and young adults who are at mid-to-high risk of developing eating disorders. Participants will complete baseline and post-intervention assessments. Primary outcomes will focus on eating disorder symptoms and body image acceptance. Secondary outcomes will include emotion regulation strategies, rumination, usability, sense of presence, cybersickness, satisfaction, and adherence. The study will also examine whether intervention effects differ according to age group and gender.

Inclusion Criteria:

• Adolescents and young adults aged 13 to 35 years.
• Spanish-speaking participants who are able to understand the study procedures and complete the assessment instruments.
• Students recruited from participating schools, universities, or related recruitment settings.
• Participants at mid-to-high risk of developing eating disorders, as assessed by the Eating Attitudes Test-26 (EAT-26) and selected subscales of the Eating Disorder Inventory-3 (EDI-3).
• Participants who provide informed consent. For minors, informed consent from a parent or legal guardian will also be required, together with the minor's assent when applicable.

Exclusion Criteria:

• Current or past self-reported diagnosis of an eating disorder.
• Current severe psychiatric symptoms or diagnosis that could interfere with participation, including suicidal, manic, or psychotic symptoms.
• Severe neurodevelopmental disorder, intellectual disability, or other cognitive impairment that could interfere with understanding or completing the study procedures.
• Physical, motor, or sensory impairment that could interfere with the assessment procedures or the use of the mixed/virtual reality intervention.
• Current psychological or pharmacological treatment for a mental health disorder delivered on a weekly or biweekly basis.
• Inability to understand Spanish.
• Failure to provide informed consent. For minors, lack of parent or legal guardian consent will also be an exclusion criterion.

Deidentified individual participant data underlying the results reported in the main publication may be made available to qualified researchers upon reasonable request, after publication of the main study results. Data sharing will be subject to approval by the principal investigators and, when applicable, by the relevant ethics committee or institutional data protection requirements. Data will be shared only in anonymized form and in accordance with the General Data Protection Regulation and Spanish data protection legislation.

Deidentified individual participant data and supporting information may become available after publication of the main study results and may be available for 5 years.

Data will be available to qualified researchers who submit a methodologically sound research proposal. Requests will be reviewed by the principal investigators. Data sharing will require compliance with applicable ethical, legal, and data protection requirements, and may require a data use agreement.

Outcome assessors will be masked to group allocation. Participants and intervention facilitators cannot be masked due to the nature of the intervention. Participants will be instructed not to disclose their group assignment or intervention-related activities to outcome assessors during assessments.