Body dissatisfaction, a primary risk factor for eating disorders, is prevalent among adolescents. Given increases in adolescent body dissatisfaction since the Covid-19 pandemic, there is a pressing need for universal body image interventions, particularly for older adolescents aged 15-17 years, as this is a peak time for the onset of adolescent body image concerns; however, currently there are no evidence-based body image programmes for this age group.

This cluster randomised control trial will evaluate the effectiveness of BodyKind, a four session, teacher led, mixed gender body image intervention for older adolescents that incorporates empirically supported principles of self-compassion, cognitive dissonance and social justice. The version of BodyKind culturally adapted for the Irish context will be evaluated in adolescents aged 15-17 years in fourth year in post-primary schools in Ireland. Primary outcomes of body dissatisfaction, body appreciation and psychological wellbeing, in addition to secondary outcomes of body ideal internalisation, self-compassion and compassion for others will be assessed at pre, post and 2 month follow up in intervention groups (who receive the BodyKind programme) and waitlist controls.

Design:

This pragmatic trial will be conducted in settings similar to the "real world" which will include use of a school setting, teacher-led delivery during classroom time, no strict exclusion criteria for students and comparison to routine lessons-as-usual. Data collection time points will be selected to align with school academic calendars and will be conducted at pre, post and two month follow up. Schools will be randomly allocated to an intervention group (who receive the BodyKind programme) or a waitlist control. Participants in intervention and waitlist groups complete measures at the same timepoints, and those in the waitlist control will receive BodyKind after all assessments are completed. A mixed methods evaluation of implementation quality will also be conducted to understand 'why' programme outcomes were observed and inform efforts to optimise programme delivery in schools in the future.

Randomization:

Prior to randomization, schools will be stratified based on school categorization (e.g., co-educational/ single sex girls/ single sex boys), size (i.e., estimated number of students in Transition Year available to participate) and location (i.e., urban/rural categorisation) to ensure the gender and geographical location of participants in each treatment group will be closely balanced. Shortlisted schools will be then randomly allocated to condition by the primary researcher using a computer-generated minimisation procedure. Minimisation is a method of randomisation that allocates participants to the treatment group that best maintains balance in prognostic factors (e.g., gender balance across condition). The first participant is allocated a treatment at random. Each subsequent participants' allocation is determined by what treatment allocation would lead to better balance between the groups in the variables of interest. Minimisation ensures excellent balance across treatment groups and is desirable when there are strong prognostic factors (e.g., gender) and modest treatment effects. Shortlisted* stratified schools will be allocated using covariate-constrained randomisation, a type of minimisation randomisation, for a two arm cluster randomized control trial, with the R statistical package cvcrand (https://cran.r-project.org/web/packages/cvcrand/cvcrand.pdf). Allocation of schools to experimental/waitlist treatment groups will be constrained by a.) the number of boys in TY in each school, b.) the number of girls in TY, and c.) the school's location categorisation (urban/rural). Schools that drop out will be replaced by schools on the waitlist based on minimisation or replacement by same category to same allocation (e.g., if an urban school drops out/fails to sign principal consent form they will be replaced by an urban school on the waitlist and to the allocation assigned to that urban school).

Data collection procedures:

Recruitment will occur at the school level. Schools will be recruited via emails (Educator School Centre's Ireland's mailing list and cold call invitations), teacher training events and advertisement on social media & website pages. Schools will be selected on the basis of (1) their expressed interest and (2) their fit with recruitment criteria.

Shortlisted schools registering interest and meeting these criteria that decline to participate after initial contact will be replaced by the next school from the waitlist of eligible schools who registered interest with the researcher. Schools will receive a €200 financial honorarium for participating.

Sample size:

The aim is to recruit 600 students aged 15-17 years in 4th year who attend second-level schools in Ireland. The aim is also to recruit 1-2 second-level teachers per school, from 12-28 schools, to deliver the BodyKind programme to adolescents.

Sample size rationale An RMASS power analysis (http://www.rmass.org/RMASS\_Manual.pdf) based on parameters; small Cohen's d effect size of .2, power .80, alpha .05, indicates that 504 students are required. To account for natural attrition and unanticipated events that reduce participant numbers (e.g., student absence due to illness) in RCTs, approximately 20% (n=100) more participants will be recruited giving a total N=600. A systematic review of consent procedures and participation rates reported that the average consent rate for active parental consent was 65.5% (range: 11-100%). The average number of students in TY in schools in Ireland is 140; therefore, allowing for a 65% response rate would indicate that a minimum of 8 schools would be required to obtain a sample size of 600. However, a recent pilot trial of a self-compassion body image intervention in Ireland recruited an average of 25 TY students per school using opt in parental consent (4 schools, N=100), indicating that n=24 schools would be required to attain a sample size of 600. Given the variability in class size in Transition Year and range in consent rates for active parental consent the investigators will seek to recruit within this range until sample size of 600 is met. To guard against drop out at a cluster level the investigators will aim to oversample and recruit at least 12 schools and a maximum of 28 schools.

Hypotheses:

The hypotheses are

1. Compared to participants in the waitlist control, participants who receive the BodyKind programme will experience statistically significant increases in a.) body appreciation, psychological wellbeing, self-compassion and compassion for others and b.) significant decreases in body dissatisfaction and body ideal internalisation from pre- to post-intervention.
2. Changes will be maintained in experimental groups at a 2-month follow up.
3. Changes in body appreciation and body dissatisfaction will be mediated by self-compassion, compassion for others and body ideal internalisation. No a-priori assumptions about the directionality of effects will be made.
4. Changes in body appreciation, body dissatisfaction and psychological wellbeing will be moderated by appearance related social media use, appearance teasing, gender, baseline body appreciation, body dissatisfaction, psychological wellbeing and implementation quality. There are no a-priori assumptions about the directionality of effects.
5. The programme will be considered acceptable and feasible by adolescents and teachers
6. The programme can be implemented with high fidelity by teachers

Data analysis plan:

Prior to conducting inferential statistics, data will be screened for missingness, outliers, normality and model assumptions. Data will be summarised graphically and by using descriptive statistics.

H1. Generalised linear mixed effects models (GLMM) will be used to determine change on outcome measures. Primary analysis will compare measures at time one (baseline) and two (post-intervention), to identify fixed effects of the intervention. Potential clustering effects will be examined and accounted for at the school level. The model will include 2 main effects (1. Repeated measures effect of time and 2. Between subjects effect of condition) and one two way interaction (time*condition). Gender effects will also be considered. With gender in the model will have three main effects and corresponding two-way and three-way interactions.

H2. Secondary analyses will examine data from time 3 (follow-up) to see if the intervention condition has maintained hypothesised changes in dependent variables. Investigators will also assess the proportion of within-group and between-group variance by calculating the ICC. As complex models can fail to converge, if investigators encounter convergence issues in our models, investigators may consider dropping the random effect accounting for the smallest proportion of between-group variance. *Note: If the recruitment target (n=600) is not met, a different statistical analytic technique, 2 (condition; experimental, control) x 3 (time; pre, post, follow up) mixed factorial ANOVA will be used. This can detect small effects, but not clustering effects, in a sample size of 238 participants, according to a MorePower analysis. Post-hoc planned comparisons will be conducted using t-tests to examine changes within groups (intervention vs control) at different time points.

H3. Mediation analyses will investigate whether changes in body ideal internalisation, self-compassion and compassion for others mediate change in body dissatisfaction and positive body image from T1 to T2.

H4. Moderation analyses will investigate whether appearance related social media use, appearance teasing, gender, school type, baseline body appreciation, body dissatisfaction, psychological wellbeing and implementation quality moderate changes from T1 to T2.

H5. Descriptive statistics will be used to assess teacher fidelity ratings

Inclusion Criteria:

• Schools will be eligible if

  1. they are a second-level school in Ireland that offers the Transition Year (TY) programme to students
  2. will deliver the intervention as part of their curriculum to students in TY
  3. teaching staff are willing to complete the 2.5-hour BodyKind teacher training programme.

Students will be eligible if

• they are in TY in a second-level school in Ireland and are aged 15-17 years
• If their parent consents to their participation AND if they provide a signed assent form .

Teachers will be eligible if

• They are qualified secondary school teacher
• They agree to complete the BodyKind teacher training
• Return a signed informed consent form

Exclusion Criteria:

• Schools will be excluded if

  • they are not a second-level school in Ireland or if they do not offer the TY programme to students
  • will not deliver the intervention as part of their curriculum to students in TY
  • teaching staff are not willing to complete the 2.5-hour BodyKind teacher training programme.

Students will be excluded if

• they are not in TY in a second-level school and are not aged 15-17 years
• If parental consent has not been obtained OR if they fail to sign a participant assent .

Teachers will be excluded if

• They are not qualified secondary school teacher
• They do not agree to complete the BodyKind teacher training
• Do not return a signed informed consent form

According to Article 9 of the GDPR, this research will involve the collection of special category data as it relates to a "person's ethnicity or racial origin, political opinions or religious or philosophical beliefs, health, genetic data, biometric data, sexual life and/or orientation, trade union membership". Given the sensitive and possibly identifying nature of the data, data cannot be publicly archived. In accordance with UCD's data retention policy, all data gathered for research will be stored in electronic form for five years from the end of the project, after which, data will be deleted.

Although raw data cannot be publicly archived, all manuscripts will be submitted to open access journals. All studies will also be pre-registered on open platforms such as OSF (https://osf.io/) and on the discipline specific, Psychology Preprint Service 'PsyArXiv' (https://psyarxiv.com/) to ensure openness and transparency.