Metacognitive Training (MCT) is a group intervention originally developed for people with psychosis. The intervention uses a “backdoor approach” focusing on the unhelpful thinking styles that underly delusions to reduce their severity, without talking about delusions themselves. This approach has gained popularity for its acceptability within a difficult population. Its non-confrontational style has been seen to overcome treatment barriers such as denial of symptom severity, low motivation to change and stigma. Like people with psychosis, those with eating disorders (EDs), hold rigid beliefs. Further, there is an unmet need for treatment among people with EDs and those with subclinical symptoms of disordered eating and body image concerns. This is due to barriers to help seeking similar to those seen in psychosis. As such, MCT was adapted for use in people with EDs to determine whether the high acceptability in other populations would translate to those with EDs and hence provide an intervention that may overcome barriers to help seeking and improve treatment uptake in this population. In adapting MCT for EDs, the ethos of targeting underlying unhelpful thinking styles without discussing disorder specific symptoms remained. Two key risk and maintaining factors associated with ED symptomology were chosen to target – perfectionism and cognitive flexibility. Six 20-minute digital, therapist-led modules were developed and tested in a sample of 35 people with Anorexia Nervosa. The intervention was found to improve Perfectionism (d = 1.29) and eating disorder pathology (d = 1.38). Whilst the intervention received positive feedback for the content, participants suggested that the intervention was too long and difficult to fit into their schedules with other treatments. As such, it was deemed that future iterations of MCT-ED should focus on becoming briefer and may be more beneficial in a different part of the treatment journey. MCT-ED was then adapted for a population considered “at-risk” of developing an eating disorder (e.g., those with elevated weight and shape concerns). This population was chosen as they often exhibit subclinical disordered eating behaviours and body image concerns that cause similar level of impairments to clinical eating disorders – but also do not seek treatment for these symptoms. Further, the risk factors targeted by MCT-ED are known to be present prior to clinical ED onset. The study found positive feedback from users who described the intervention as engaging and helpful, whilst recognising the benefit of the brief format. Further, the intervention provided improvements in perfectionism (d = .60) and overall stress (d = .44). Small, non-significant improvements were also found in eating disorder cognitions relative to a waitlist control (d = 0.34). MCT-ED has potential to be an efficacious and highly scalable intervention for people with and at-risk of developing an ED. Further, by countering barriers to help-seeking, this intervention may be able to increase treatment uptake in a challenging population to reach. This talk will provide context on brief digital interventions for EDs, and discuss the process of developing feasible, acceptable digital interventions with users in mind and the role of co-design in furthering MCT-ED and other interventions to maximise usability and effectiveness.