Anorexia Nervosa
Anorexia Nervosa (AN) is a serious psychiatric and physical illness characterised by an overvaluation of weight and shape with associated behaviours including restricted eating, purging, and increased energy expenditure, all typically associated with a fear of weight gain and/or a drive to lose weight (1,2).
The ICD-11 definition describes Anorexia Nervosa as characterised by significantly low body weight for the individual’s height, age and developmental stage that is not due to another health condition or to the unavailability of food. A commonly used threshold is body mass index (BMI) less than 18.5 kg/m2 in adults and BMI-for-age under 5th percentile in children and adolescents. Rapid weight loss (e.g., more than 20% of total body weight within 6 months) may replace the low body weight guideline, provided that other diagnostic requirements are met. Children and adolescents may exhibit failure to gain weight as expected based on the individual developmental trajectory rather than weight loss. Low body weight is accompanied by a persistent pattern of behaviours to prevent restoration of normal weight, which may include behaviours aimed at reducing energy intake (restricted eating), purging behaviours (e.g., self-induced vomiting, misuse of laxatives), and behaviours aimed at increasing energy expenditure (e.g., excessive exercise), typically associated with a fear of weight gain. Low body weight or body shape is central to the person's self-evaluation and low body weight is often inaccurately perceived to be normal (2).
Anorexia Nervosa can affect relationships with family and friends and can impact education and work and cause significant health complications, leading to high levels of public health service use (2). In the long-term, complications from malnutrition caused by anorexia nervosa can include osteoporosis, infertility, cardiovascular problems, anaemia, immunosuppression, as well as growth and developmental difficulties in children and young adults (1).
A holistic assessment of individual needs should include an assessment of physical health, psychological presentation, and levels of functioning in different aspects of life such as home and school. This assessment should inform the collaborative development of a biopsychosocial formulation. In some situations, e.g., significant physical risk, and with some treatment modalities, there may be a stronger emphasis on quickly restoring physical health in acute starvation. The recent Medical Emergencies in Eating Disorder (MEED) guidance provides advice on assessing all eating disorders that can lead a patient into a state of clinical emergency (3).
Research indicates a higher mortality rate with Anorexia Nervosa than with other mental health disorders (4). In the United Kingdom, it is estimated that 1.25 million people have an eating disorder and Anorexia Nervosa is estimated to account for 8% of these cases (5). Eating disorders can develop at any age, with the greatest incidence of Anorexia Nervosa in adolescents and young adults (6). The lifetime prevalence of anorexia is estimated as 4% for females and 0.3% for males (7). Most research has included females, with more research required which includes or focuses on presentations in males (8).
This information is for commissioners, managers, trainers, and health care practitioners to consider the evidence base for the delivery of psychological interventions for people with Anorexia Nervosa. This information is also for people diagnosed with Anorexia Nervosa, their families, and carers.
Exclusions for topic: This topic does not cover pharmacological interventions or interventions which are not informed by psychological theory. There are a wider range of non-psychological interventions and supports that are beyond the scope of this topic and full guidance on best practice can be found in SIGN (9). This topic introduction exclusively applies to the management of Anorexia Nervosa. Guidance for other eating disorders such as Bulimia Nervosa and Binge Eating Disorder can be found in other Matrix topics.
There are a range of interventions with enough evidence to be included in the treatment tables for Anorexia Nervosa (AN). To be consistent with our focus on interventions with the highest levels of efficacy and the strongest levels of evidence, where these exist, psychological interventions for managing AN with low strength evidence and low levels of efficacy have not been included. The evidence is obtained from systematic reviews/meta-analyses and Randomised Control Trials of psychological interventions and this is summarised for CYP and Adults below. In any scenario of extreme starvation and risk, physical stabilisation is the priority, with close monitoring and support in an outpatient setting, and where necessary inpatient care would be considered.
Overview of Evidence for Children and Young People
NICE (2017) and SIGN (2022) recommend offering family-based treatments (FBT) to children and adolescents with AN. Family based treatments can involve a range of approaches, derived from different theories, that involve the family in treatment (9,10). The SIGN recommendations draw upon meta-analyses that assessed the effectiveness of FBT compared to other interventions or treatment as usual (11,12). These reviews suggest that FBT may be more effective that other treatments for reducing rates of remission and aiding weight gain but caution that the current evidence is of low-quality (with small sample sizes and risk of bias). A recent randomised control trial comparing FBT with individual therapy (Adolescent-Focused Therapy) found FBT to be more effective in leading to full remission at 6- and 12-month follow up. More participants were hospitalised during the treatment phase with Adolescent-Focused Therapy (37%) than FBT (15%) (13). SIGN (2022) reports that FBT is established practice in clinical services and is supported by manualised approaches in out-patient settings (9).
The focus of research in CYP presenting with AN is developing to include investigation of factors that may lead to improved outcomes in specific circumstances. Benefits have been found from adding a parents/carers-only session for families receiving FBT where there is higher expressed emotion, longer pre-treatment illness duration or increased obsessive-compulsive symptom severity (14). Additional parent skill and mealtime-focused sessions can be employed for people with lower early weight gain (14). There may also be benefit from providing Multifamily therapy (MFT) in addition to family therapy for AN in terms of end of treatment outcomes, but the additional benefits were not sustained at 6-month follow up (14). This information has been used to guide the recommendations for treatments for particular presentations in the table below and further information on the details of the types of FBT approaches and evaluation of the current literature is available in SIGN (2022) (9).
Cognitive Behavioural Therapy adapted for eating disorders (based on Fairburn’s model of CBT-E) with a duration of 20-40 sessions has also been evidenced to be effective in the treatment of adolescents with Anorexia Nervosa, as reported in a systematic review of case series studies which looked at the functioning of adolescents with AN before and after receiving CBT-ED (15). These studies did not have a control group to act as a comparison. The review reported 63-97% of people with AN completed treatment and there were improvements in psychological and weight outcomes in adolescents who received CBT-E that were sustained at over 1-year follow-up (15). However, currently no Randomised Control Trials (RCTs) have yet been published which explore efficacy of CBT-E for adolescents.
There is a lack of robust evidence to support the recommendation of other psychological therapies for the treatment of Anorexia Nervosa in adolescents (9).
Overview of Evidence for Adults
International guidelines are consistent in the recommendation that psychological interventions should be a first-line treatment for AN. Recent Scottish Guidance (9) recommends eating disorder focused Cognitive Behavioural Therapy (CBT-ED) as a first line therapy for adults with Anorexia Nervosa (AN). UK guidance NICE (2017) recommends one of; CBT-ED, the Maudsley Model of Anorexia Nervosa Treatment for Adults (MANTRA), or Specialist Supportive Clinical Management (SSCM) for adults with AN.
Evidence for treatment outcomes is drawn from studies covering a range of eating disorders and studies focusing specifically on AN. A comprehensive review of enhanced cognitive behaviour therapy for eating disorders (16) concluded that there was a significant reduction in symptoms for eating disorders, including AN. Recent reviews by Solmi et al. (2021) and Monteleone et al. (2022) challenge the view that one individualised therapy is superior to another for AN, highlight the similarities in outcomes between psychological therapies and treatment as usual comparisons delivered in specialist clinical services, and identify key areas for research development. In trials CBT-ED was found to have lower drop out from treatment compared to psychodynamic orientated therapies (17,18) and to facilitate greater speed of weight gain and more rapid change in core presenting difficulties (19) than other structured therapies for AN. Considering all the review findings, there is a cautious continued recommendation of CBT-ED as a first line intervention, along with the need for collaborative formulation and informed patient choice to guide treatment selection. NICE (2017) recommends that CBT-ED should be offered in individualised format in up to 40 sessions (10).
As an alternative to CBT-ED, Specialist Supportive Clinical Management (SSCM) and MANTRA have been reported to produce similar outcomes (for weight and eating disorder difficulties) when compared to CBT (20), and when compared with each other (21,22). These studies grow the evidence base for MANTRA and SSCM and provide support for their recommendation as alternative interventions for the treatment of Anorexia Nervosa in adults, when CBT-ED is found to be ineffective, unsuitable or unacceptable (9). One study further reported significantly higher acceptability for MANTRA compared to SSCM, which may indicate possible preference for MANTRA in some cases (21). In young adults or those where family involvement is possible, a recent meta-review of meta-analyses (18) indicates that it is worth considering FBT (see CYP recommendations for further information).
Consideration of focal psychodynamic therapy as another alternative psychological intervention for Anorexia Nervosa in adults has also been suggested (9), supported by evidence of comparability to enhanced CBT as it relates to recovery (4). Whilst focal psychodynamic therapy appears to be advantageous as it relates to long-term outcomes, CBT-ED has been shown to facilitate faster recovery compared to focal psychodynamic therapy (4).
Lastly, Interpersonal Psychotherapy (IPT) for the treatment of adults with Anorexia Nervosa has shown promising results longer term (23,24) where, despite IPT performing less effectively post intervention, there were similar benefits to other structured psychological therapies for AN and long term follow up (average 6.7 years). There are methodological concerns in the studies involving IPT which limit the strength of evidence for this intervention and reduce confidence in the conclusions drawn. IPT may be considered an alternative psychological intervention for the treatment of Anorexia Nervosa if first-line recommendation is unsuitable (9). The potential lag effect on outcomes in comparison to other therapies should be highlighted to support informed patient choice.
There are several other psychological therapies which show promise and are mentioned in SIGN (2022) as could potentially be offered to people with Anorexia Nervosa e.g., Cognitive Analytical Therapy, Schema Therapy and Mentalisation Based Therapy but are not yet at a point of demonstrating efficacy via robust RCTs therefore are not included in these recommendations (9). While not specifically addressed here, there are also therapies such as Cognitive Remediation Therapy and Dialectical Behaviour Therapy, which could be considered as treatment options for individuals with co-occurring difficulties, guided by a holistic formulation.
Overview of Evidence for Older People
The information available on the specific treatment of eating disorders in people over the age of 65 years is limited (25). The quality of case reports to date makes it difficult to suggest specific assessment or treatment guidelines for this population and therefore clinicians should follow the guidance for adults. Clinicians are advised that there are differences in presentation of psychological problems in later life and to consult Delivering Effective Psychological Therapies and Interventions to Older People for further information on factors relevant to practice.
Overview of Evidence for Harms and Adverse Effects
Psychological therapies have the potential to have adverse effects. Until recently, information on potential harms and rates of adverse effects have not been gathered systematically. Although reports of adverse effects are increasingly included in research trials and gathered as part of service provision we do not know if psychological interventions cause more, fewer or similar numbers of adverse effects than no treatment or another treatment, because the evidence in this area is of very low quality at present.
| Recommendations | Who for? | Intervention | Type of psychological practice | Level of Evidence | Level of Efficacy |
| First line intervention | CYP with AN where caregiver support available | Family Based Therapy (11,12,26,27) | Specialist | A | Low-High for weight gain |
| Alternative | CYP with AN in older adolescents where caregiver support is not available or client choice, or FBT has not been effective | Cognitive Behavioural Therapy for Eating Disorders (15) | Specialist | B | N/A |
| Alternative | CYP with additional features such as severe OCD or high levels of expressed emotion | Systematic Family Therapy or augmented FBT (14) | Specialist | B | N/A |
| Recommendation | Who for? | Intervention | Type of psychological practice | Level of Evidence | Level of Efficacy |
| First line intervention | Adults with AN | Cognitive Behavioural Therapy for eating disorders (4,16,19,20,23) | Specialist | A | Low – High for BMI/weight gainLow- medium for clinical symptoms |
| Alternative | Adults with AN | Specialist Supportive Clinical Management (SSCM) (20-23,28) | Enhanced/specialist | A | Low-High for BMI/weight gain |
| Alternative | Adults with AN | MANTRA (20-22) | Enhanced/specialist | A | Low-High for BMI/weight gain |
| Alternative (lower efficacy) | Adults with AN | Focal psychodynamic therapy (4,28,29) | Specialist | A | Low |
| Alternative (lower efficacy and evidence less well established) | Adults with AN | Interpersonal psychotherapy (23) | Specialist | B | Low-Medium BMI/weight gain |
Advisory Group: BEAT
Technical Group: Fiona Calder, Fiona Duffy, Sandra Ferguson, Charlotte Nevison, Emma Mawdsley, Leeanne Nicklas, Joy Oliver, Eleanor Simpson, Marie-Claire Shankland.
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