Eating disorders (EDs) are serious psychiatric illnesses that disproportionately affect young women1, 2. Early
intervention, when individuals show some signs and symptoms, but before behaviors become more
automatic and entrenched can mitigate significant morbidity and mortality3-6. However, there are limited
early ED interventions and ED treatment broadly suffers limited access and engagement7-10. Digital
interventions have high potential to overcome access barriers and appeal to young people at greatest
risk for ED onset2, 11, yet are undeveloped. Many digital interventions simply convert information or in-person
activities to an online format or focus on screening and referral, and interventions are primarily based in
traditional cognitive-behavioral therapy (CBT)10, 12. Few (if any) have taken a user-centered design approach
to development or used gamification, which may increase engagement and learning through operant
learning principles. In an initial proof of concept study, we piloted a novel digital, gamified intervention based
on Acceptance and Commitment Therapy (ACT)13. Rather than the typical approach to the body weight
concerns that underlie EDs, the intervention used gamification to experientially train body-image flexibility
(BIF) (i.e., the ability to have distressing thoughts/feelings about the body, without unnecessary attempts to
avoid or escape these experiences, and pursue other personally meaningful values or goals). This is a new
direction with preliminary support, and would be a paradigm shift in early ED intervention, which has focused
on changing or eliminating body-image distress. This Phased R61/R33 (NIH Stage 1A-B) takes a user-
centered design and experimental therapeutics approach to further develop and optimize the intervention
for young women in the US with ED symptoms. In the R61 Phase of the study, draft sessions are built with
streamlined content, and enhanced graphics and interactive features, and we conduct iterative user testing to
maximize acceptability and impact on BIF (Aim 1). We then use a multiple baseline experiment across
participants to test the effect of the intervention (“FlexED”) on BIF, our targeted mechanism of change, and
establish treatment dose (Aim 2). During the R33 Phase, we conduct a pilot RCT comparing FlexED to an
online educational control. We test the effect of the intervention on BIF and the associated clinical benefit, and
assess whether the intervention results in decoupling of body-image distress and behavior as an additional test
of our mechanism of change (Aim 1). We also test a virtual body-Behavioral Approach task as an assessment
of BIF in a personally meaningful or valued context that may be used in future investigations (Aim 2). Finally,
we assess the acceptability of the final FlexED intervention, as indicated by retention (Aim 3). This proposal
prepares for a larger trial with longer-term follow up, with the ultimate aim of establishing a cost-effective,
widely available early intervention to decrease the societal impact of EDs1.