The aim of this study is to test a novel guided self-help intervention for patients with Anorexia Nervosa. The 6-week intervention includes the use of self-help materials (i.e. a workbook and short video-clips) and weekly guidance from a peer mentor (i.e. a person recovered from Anorexia Nervosa). Self-reports will be completed at baseline, end of 6 weeks, and 6- and 12 months follow-up. Participants interested in taking part will be randomly allocated to one of two groups.

This trial investigates whether a guided self-care intervention (Recovery MANTRA) is a useful addition to treatment as usual (TAU) for individuals with anorexia nervosa (AN). Recovery MANTRA, a 6-week self-care intervention supplemented by peer mentorship, is a module extension of the Maudsley Model of Treatment for Adults with AN and targets the maintenance factors identified by the cognitive-interpersonal model of the illness.

Patients accessing outpatient services for AN are randomised to either TAU or TAU plus Recovery MANTRA. Outcomes variables include changes in body weight at the end of the intervention (primary) and changes in body weight and eating disorder symptoms at immediate and extended follow-ups (6-months and 12-months; secondary). Change is also assessed for the domains identified by the theoretical model, including, motivation, hope, confidence to change, positive mood, cognitive flexibility, therapeutic alliance and social adjustment. Feedback from peer mentors is gathered to understand the impact of providing guidance on their own well-being.

Results from this exploratory investigation will determine whether a larger clinical trial is justifiable and feasible for this affordable intervention which has potential for high reach and scalability.

Inclusion Criteria:

- Referral to one of the participating specialist adult outpatient eating disorder clinics with a primary DSM-5 diagnosis of Anorexia Nervosa or OSFED (Other Specified Feeding or Eating Disorder) with a body mass index (BMI; kg/m2) of 18.5 or below. OSFED will be defined as having features of Anorexia but missing at least two of the four diagnostic criteria.

Exclusion Criteria:

• Insufficient knowledge of English
• Severe mental or physical illness needing treatment in its own right (e.g. psychosis or diabetes mellitus).