This dissonance-based body image program was created from focus group feedback (Ciao, Ohls, & Pringle, 2017) and piloted in an initial randomized-controlled trial. Based on the Body Project (Stice et al., 2006), it retains key dissonance activities while adapting exercises to have a more inclusive focus (e.g., expanding the gender focus, exploring diversity characteristics within appearance ideals, adjusting activities to be inclusive of diversity).

Around 10% of the original EVERYbody Project manual was modified to create the Peer Facilitator version for the current trial. Changes focused on adding individual exercises to draw out the critique of diversity in cultural ideals, refining prompts to be more suitable for peer facilitation, and flagging sections of the manual for more "expert" peer facilitation.

Peer facilitators received 16 hours of training on the EVERYbody Project manual and peer facilitation guidelines (e.g., group management, handling problems, etc.).

Video + expressive writing groups were facilitated by a peer leader following a detailed script. This intervention was designed as an active but low-dissonance comparison condition. Participants viewed two separate documentary movies related to gender and/or appearance-related pressures (one during each session): (1) The Illusionists (2015 ), and (2) The Mask You Live In (2015). Participants engaged in a brief (10 minute) reflective writing exercise after each film. In order to keep dissonance low, participants were told that their reflections would not be shared with anyone and they were not turned in.

Peer facilitators received brief (1 hour) training on the video group manual.

Brief behavioral intervention (4 hours across two meetings)

Eating disorder symptoms were assessed with the Eating Disorders Examination Questionnaire (EDEQ; Fairburn & Beglin, 1994). The Global score of the EDEQ was used in this study (average across all 28 items).

The Satisfaction and Dissatisfaction with Body Parts Scale (SDBPS; Berscheid, Walster, & Bohrnstedt, 1973) assessed satisfaction and dissatisfaction with nine parts of the body that are commonly endorsed as concerning (e.g., stomach, thighs, hips). The average score was used in this study (average across all 9 items).

The two Internalization subscales of the Sociocultural Attitudes Toward Appearance Questionnaire-4 (SATAQ-4; Schaefer et al., 2015) assess internalized cultural messages surrounding appearance and attractiveness. The two internalization subscales were combined for this study (average across all 10 items), following prior research by Kilpela et al. (2016). This survey was assessed at all outcome time points (Survey 1, 2, and 3), plus midway through the intervention (following Session 1 of the program).

Negative affect was assessed with 20 items from the fear, guilt, and sadness subscales of the Positive and Negative Affect Schedule-Revised (PANAS-X; Watson & Clark, 1992). The average of all 20 items was used in this study.

A series of feedback questions were used to gauge satisfaction with the EVERYbody Project (based on Ciao et al., 2015). These questions included four Likert scale items about enjoyment (e.g., "I enjoyed the EVERYbody Project") rated from 1 (strongly disagree) to 5 (strongly agree) as well as open-ended questions (e.g., "Was any part of the EVERYbody Project particularly helpful/useful? If so, which part and why?") These questions were administered immediately following participation in the EVERYbody Project as a part of the post-intervention survey (Survey 2).

At post-intervention (Survey 2) and one-month follow-up (Survey 3), three questions gauged application of information learned in the program (e.g., "How often do think about the things you learned in the EVERYbody Project?" rated on a scale from 1 (not at all) to 5 (all the time).