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Managing anorexia nervosa
  1. Dasha Nicholls1,
  2. Lee Hudson2,
  3. Fermeda Mahomed1
  1. 1Department of Child and Adolescent Mental Health, Great Ormond Street Hospital, London, UK
  2. 2Department of General Paediatrics and Adolescent Medicine, University College Hospitals, London, UK
  1. Correspondence to Dr Dasha Nicholls, Feeding and Eating Disorders Service, Department of Child and Adolescent Mental Health, Great Ormond Street Hospital, Great Ormond Street, London WC1N 3JH, UK; d.nicholls{at}


Clinical confidence and coordinated multidisciplinary care can influence the course of anorexia nervosa in children and adolescents. Sicker and younger patients with anorexia nervosa often present first to a paediatrician, requiring early recognition and appropriate management. Paediatric knowledge and skills are also needed to manage the impact of eating disorders on growth and development. This review provides practical guidance on the management of anorexia nervosa for paediatricians, in the areas of assessment, acute management and re-feeding, and long-term monitoring. In the absence of a strong evidence base for some of these recommendations, local protocols based on best practice guidelines can reduce anxiety, increase cooperation and reduce risk.

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Eating disorders challenge both the medical and psychological skills of health professionals. The multidisciplinary networks caring for these patients vary by healthcare setting and by country. What is unequivocal is that the sickest patients require the skills of acute paediatricians, and that the longer term impact of eating disorders on growth and development also needs paediatric expertise. Moreover, sicker and younger patients with eating disorders often present first to a paediatrician, requiring early recognition and appropriate management. A number of guidelines exist for care of patients with eating disorders.1,,5 Some have limited application to children and adolescents, or provide little detail about medical aspects of care. They broadly agree on the domains of relevance, but vary in specific thresholds for concern. This is an area where the evidence base is limited and the risks quite high, so clinical trials are difficult. This article addresses aspects of eating disorder care that typically involve paediatricians, while acknowledging that the primary task is to engage and motivate young people to address the thoughts and feelings that characterise eating disorders, more typically the domain of mental health professionals. The way in which physical and mental health services work together is arguably one of the most important elements of effective care. To that end, a shared understanding of eating disorders is essential.

Anorexia nervosa, bulimia nervosa and related eating disorders (atypical eating disorders or eating disorder not otherwise specified (EDNOS)) have at their core a morbid fear of weight gain. Abnormal eating behaviour that does not have this feature would not currently be diagnosed as an eating disorder. Although such presentations form a significant proportion of those presenting clinically, there is little or no research to guide clinical approaches.

Once considered a phobic disorder of maturation, anorexia nervosa is increasingly recognised before puberty has begun. Nonetheless, anorexia nervosa retains at all ages characteristics of a developmental disorder, impacting psycho-physiological maturation, cognitive development including problem solving and conceptual understanding, and social, personality and emotional development including self-concept and identity formation. It can result in delay or regression in some or all of these areas. The good news is that once recovered, most stay well, and that most recover within 5 years.6 Clinical features often found in young people with anorexia nervosa include depression, obsessive compulsive disorder or traits, social anxiety, and difficulties with change, ritualised behaviours and perfectionism. For a few, the illness represents a more severe and, rarely, permanent developmental deviation. It is study of this severe and chronic group that has led to interesting insights into the neurobiological and neuropsychological underpinnings of anorexia nervosa.7

Bulimia nervosa, on the other hand, requires a degree of psychological maturation that anorexia nervosa does not, including capacity for self-evaluation, often manifest as shame or guilt. It almost never occurs before menarche. It can arise out of anorexia nervosa, as in the original description,8 or develop secondary to repeated dieting behaviour.9 It is by nature episodic, acute or chronic, and relapsing. Common associations include depression, self-harm, substance misuse and other risk behaviours. Most EDNOS or atypical cases look like anorexia nervosa in younger patients, often weight restored but still with marked psychopathology, and in older adolescents present with a variety of bingeing, purging, starving and exercising behaviours, with or without weight loss, often with marked comorbidity.10 EDNOS presentations are the most common across the age range.

What all these eating disorders have in common are drive for thinness, perfectionism and a fear of being out of control. Effective clinical care recognises the importance of structure and clarity, reliability and predictability, and patients' anxiety about the unfamiliar. Communication style, treating young people with respect, providing information, involvement in decision making and offering choice, where appropriate, are crucial. This paper will focus on anorexia nervosa, since this is the eating disorder most likely to come to paediatric attention, and which causes greatest anxiety among those not confident in its management. It is important to note, however, that all eating disorders are associated with significant mortality in the longer term: crude mortalities are estimated at around 4.0% for anorexia nervosa, 3.9% for bulimia nervosa and 5.2% for EDNOS.11


Paediatricians are expert in the assessment of infants and young children with failure to thrive, identifying the basis as inadequate intake. Making a diagnosis of anorexia nervosa can be difficult as it is often covert, but if not considered will be missed, or sidelined, while other medical diagnoses are pursued. In the meantime the patient continues to lose weight, increasing the risk of complications, and increasing family anxiety. A single consultation about eating behaviour or weight and shape concerns is a strong predictor of the subsequent emergence of anorexia nervosa.12 Dieting and body image concerns are so common that by the time a parent is concerned enough to seek help, the eating disorder is often quite established. It is important, however, to consider other medical reasons for weight loss. A differential diagnosis of common reasons for weight loss in older children and teenagers is shown in table 1.

Table 1

Common differential diagnoses for weight loss in older children and adolescents

Nutritional assessment

Assessment of nutritional status is the first step in determining risk, and considers the past, the present and the future, not just current nutrition.

The history will indicate duration of low weight and rapidity of weight loss. Rapid weight loss is potentially more destabilising, although acute on chronic weight loss is common. Loss of more than 1 kg per week over a few weeks or if already underweight is considered a serious risk. Menarchal status is the best indicator of sufficiency of nutrition in girls; an equivalent marker for boys or premenarchal girls is cessation of growth, but this can be difficult to detect. Failure to gain weight often precedes weight loss.

Current nutritional status is assessed through weight and height, physical examination and a dietary history. The body mass index (BMI: weight (kg)/height (m)2) is used in adults with eating disorders, but in the paediatric age group BMI changes with age. Standardised charts for BMI in the UK13 are not always applicable in some racial groups. The problem arises with how to quantify underweight in those below the second BMI centile. The most recent UK BMI charts include three grades of thinness, based on adult BMIs of 16, 17 and 18.5.14 The alternative is to express weight for height as a percentage of ‘ideal weight’ for height. There are a number of ways of calculating this, each giving a slightly different figure.15 We recommend using % BMI (calculated as BMI/% median BMI for age and gender), as patients can understand it, and it allows comparison with the literature. The third option is to express underweight as SD scores, but few papers use this method.

BMI and related weight/height ratios are not a measure of body composition. When weight is lost, fat and muscle are both lost, even in children.16 What constitutes a healthy weight is complex in children and young adults with anorexia nervosa and cannot be determined by BMI alone. In postmenarchal adolescents, the return of regular menses is useful, but this may not occur until 6 months after regaining an appropriate weight. Since BMI is normally distributed, for most young people resumption of menses occurs at 95% BMI or above; about 15% will menstruate below this.15 Some use ultrasound scans to identify follicular activity while awaiting resumption of menses.17 Use of standardised growth charts for height and weight are appropriate where previous growth information is available. The height percentile can be a useful guide to expected weight if growth has not yet been significantly affected.

Table 2 gives suggested parameters for physical examination. A history of blackouts on standing, fatigue, hair loss, etc, are important to identify, but correlation between symptoms and weight loss, and between symptoms and signs is poor.18 Dehydration is difficult to assess in any child, and is especially so in those with malnutrition.19 Skin is often dry and thin in anorexia nervosa, and hypotension usually chronic due to poor cardiac contractility with ventricular dysfunction because of myocardial atrophy rather than secondary to acute hypovolaemia.20 Bradycardia is thought to be due to increased vagal activity to reduce cardiac output and preserve energy, and reduce demand on a malnourished heart. Intravenous fluid boluses are therefore usually unnecessary, and indeed sudden fluid changes can be dangerous in this context. Rehydration if required is best done orally or via nasogastric tube with oral rehydration solution.

Table 2

What to look for on physical examination

A 3-day food diary is ideal, but some dietary assessment is possible without a qualified dietician. Intake can be estimated by asking about a typical day's intake (including snacks and drinks), specifying portion sizes. Types of foods consumed give diagnostic clues, in particular checking about vegetarianism, veganism, food intolerances and any other specific food groups avoided. Sometimes young people adhere to specific calorie targets, which may have changed over time. Children often restrict fluid as well as food. Older adolescents, on the other hand, may fluid load to falsify weights or to fill themselves up to prevent hunger: both behaviours carry risks. Ask about compensatory behaviours, especially directly after mealtimes, such as running up and down stairs or doing sit ups, or going to the toilet.

Finally it is important to project forward to the future, to predict whether a young person is likely, unless something changes, to be eating less in the next few days than they are currently. A ‘wait and see’ attitude for a patient who is deteriorating is only going to increase anxiety in carers, and convey to the person with an eating disorder that they must try harder.

Acute management of the medically compromised patient

For eating disorders, the acute risks can be a result of low weight or secondary to compensatory behaviours such as vomiting or purging. Severe malnutrition is a medical emergency. Table 3 shows the principle medical complications of eating disorders.

Table 3

Complications of underweight and resulting from purging/bingeing

Bloods and an ECG can help in assessing both the immediate medical risk and the risks during re-feeding (table 4), but normal blood parameters are not necessarily a cause for reassurance if other signs of malnutrition are present.

Table 4

Recommended investigations

Admission to hospital is advised for medically compromised patients, or when the diagnosis is unclear and a period of observation may be of value. It is also an option when families seem to be struggling to cope, or a young person is in need of a safe place because of psychiatric or social need. There is much variation between guidelines in actual and absolute values to indicate medical compromise, particularly with regard to heart rate and blood pressure. Table 5 shows our suggested thresholds for admission: it is worth noting, however, that some patients eat better at home, and the challenge then is to ensure that the risks have been fully assessed and that adequate monitoring is in place.

Table 5

Indications for paediatric admission


Re-feeding is the process by which the trajectory of nutritional decline begins to be turned around, and should begin if there is evidence of physical compromise with or without metabolic changes. For both physical and psychological reasons, this process needs to be undertaken slowly and carefully. Sudden reversal of prolonged starvation by administering food leads to a reciprocally sudden requirement for electrolytes involved in metabolising it, the so called re-feeding syndrome.21 Phosphate levels can fall very rapidly within the first week of re-feeding,22 with neurological and cardiovascular consequences. Those most at risk of re-feeding syndrome are patients with very low weight for height, minimal or no nutritional intake for more than a few (3–4) days, weight loss of over 15% in the last 3 months and those with abnormal electrolytes prior to re-feeding.

It remains unclear exactly what a safe initial rate of calorific provision prevents re-feeding syndrome, especially in younger children. Recommended rates of re-feeding vary from 10 to 60 kcal/day up to nearer 70–100 kcal/kg/day. Convention has been to start slowly and then build up cautiously, with regular monitoring of electrolytes. However, more aggressive approaches may be safe,23 and delay in feeding needs to be balanced with the less recognised syndrome of ‘underfeeding’, with subsequent ongoing complications and poorer outcome. Energy requirements of adolescents in puberty are greatly increased and calculating energy requirements during growth is a problem. We recommend the involvement of a dietician with experience and expertise in managing eating disorders as early as possible. Where expertise is not available locally, it can be sought from specialist centres.

The options for re-feeding are oral food and fluid, oral nutritional supplements or nasogastric tube. Other options (eg, percutaneous endoscopic gastrostomy (PEG) tube insertion) would only normally be considered in severe or chronic cases. This is an area of potential choice for the young person, and although oral is preferable, some choose to be tube fed because it relieves them of the responsibility of eating. Other choices include where and with whom they eat, provided intake is very closely monitored. For younger patients exclusion of parents can be counterproductive, because of the increase in anxiety separation can cause.

Nasogastric feeding is usually a short-term measure, its use curtailed as oral intake improves. Nasogastric feeds can be intermittent, bolus or continuous depending on the needs of the young person. Many eating disorder specialists advocate day time bolus feeds at mealtimes to mimic physiological demand and so that choice can be offered on each occasion (‘do you want to eat, drink or be fed this time?’). Post meal support such as relaxation, distraction or social activity, is essential no matter what route. Night time feeds are less helpful in anorexia nervosa than in many paediatric conditions, because patients often need to stay awake to monitor the feed and tiredness does not generally improve emotional coping.

In the first 1–2 weeks of re-feeding, electrolytes need to be monitored regularly, at least daily initially. If features of re-feeding syndrome occur, feeds should be slowed, or in severe cases stopped, with electrolyte imbalances corrected. Electrolyte replacement can be done orally, although the clinical situation (for example the presence of arrhythmia or where purging is a problem) may necessitate intravenous correction. Some units will start patients on prophylactic oral phosphate supplements, whereas others will begin them if the phosphate level begins to fall. Our experience is that patients with severe anorexia nervosa will usually require oral phosphate supplementation and it can take some time to catch up, so the earlier they are started the better. Administering oral electrolyte medications, however, can be unpalatable and disturbing for patients who have just been admitted to hospital with an eating disorder, so a balanced and pragmatic approach is required.


A large proportion of patients with eating disorders exercise excessively, and there is recognition of the adverse effects of strenuous physical activity in malnourished individuals. Sport and exercise is integral to the pathogenesis and progression of self-starvation.24 Physical activity should therefore be assessed (this may include an interview with the family) and included into a management plan. Features of excessive exercise include: exercise that interferes with social, educational and vocational activities, secretive exercise, compulsive exercise, exercising when injured, increased anxiety when prevented from exercising, and exercising due to preoccupation with low weight and physical appearance. Excessive exercise increases the risk of stress fractures especially in those with osteopenia.

In the acute phase of the illness, unsupervised exercise in medically compromised patients requires close monitoring. Units vary in their approach to managing physical activity.25 Supervised, graded, physical activity is probably more helpful than total restriction,26 which will increase anxiety. The appropriate level of activity needs to be discussed and agreed within the multidisciplinary team and with parents/carers, alongside work with the young person to help them identify exercise that is unsafe or excessive, and create a plan to help manage and address unrealistic beliefs around exercise. Dietetic advice needs to factor exercise levels into assessment of nutritional requirements.

Managing and monitoring long-term growth and development

Growth slows down and even stops during starvation, and growth delay can be the first sign of weight loss. This is of clinical importance in premenarchal girls and in boys, since menarche is a later pubertal event. With weight restoration ‘catch-up growth’ can occur, and may be the best marker that a healthy weight has been reached. Stunting as a consequence of anorexia nervosa is well described, although much ‘stunting’ is actually delayed growth27 and there are case reports of people going through puberty in their late 20s (and, anecdotally, reaching menarche at over 50). The biological insult needed to reprogramme growth is unclear; our best guess is 4 years of starvation before completion of growth.16 Rating of pubertal development and bone age are key in assessing delay. Growth can be an important motivator for recovery.

The timing of puberty in any individual reflects a strong genetic component, with additional effects from nutrition, psychological status and socio-economic conditions. Rating puberty gives important information about expected biological and cognitive function and expected outcomes (a patient in stage 2 puberty would not be expected to menstruate as a sign of health). Serial pelvic ultrasound can be used to monitor pelvic organ maturation28 and predict maturity required for onset of menses.17 Because puberty in boys is about 2 years later than in girls, and peak height velocity is later (around age 14/stage 3–4 in boys, 11.5 years/stage 2–3 in girls), boys are more vulnerable to the impact of anorexia nervosa on growth and development. Three monthly height measurement and pubertal rating plus a baseline bone age x-ray and parental height measurement all give important information on expected and actual progress through puberty.

Bone density

The consequences of prolonged malnutrition on bone density can be swift and severe.29 Adolescence is the period of life with the highest rate of bone acquisition; leaving adolescence with poor bone density may herald early osteoporosis with increased fracture risk in later life.30 Treatment with bisphosphonates31 and oestrogen supplementation32 have not shown to be of benefit. The most effective treatment for and prevention of decreased bone density is achieving a healthy weight, the sooner the better, with resumption of menses.33 There is no evidence for the role of either calcium supplements or vitamin D supplements in improving bone density, although some guidelines recommend them.34 A diet rich in calcium is important. DEXA scans are useful in highlighting poor bone density and can be a helpful, tangible measure to explain to young people and their families the danger of their illness, as well as to monitor progress. Response of bone to weight restoration is slow, and should not be expected until a year or more after a healthy weight has been achieved.35 Other ‘traditional’ guides to growth such as hand x-rays are useful in monitoring progress.

Team working

One of the biggest challenges in this early stage is managing anxiety and coordinating care within the multidisciplinary team. Our understanding of the importance of involving families in treatment at all ages,36 and awareness that involving young people in decision making increases cooperation and motivation, have been pivotal in improving outcomes. This underpins all interactions from the start, and is not just the domain of family therapy sessions. Identifying someone who has made a connection with the young person, and someone to support parents are priorities; they may or may not be a trained mental health professional. The UK NICE guidelines recommend that ‘where management is shared between primary and secondary care, there should be clear agreement among individual healthcare professionals on the responsibility for monitoring patients with eating disorders. This agreement should be in writing.. and should be shared with the patient and, where appropriate, his or her family and carers’.1 This principle also applies to care shared between paediatric and psychiatric colleagues.


The peak age of onset for anorexia nervosa is around the cusp between adolescence and adulthood, making transition to adult services a common requirement. Transition is a time of increased risk for patients with anorexia nervosa, and early planning is needed. In addition to clarifying treatment needs, liaison with medical colleagues is needed about the management of those at high risk.37 Adult physicians may not feel skilled in the assessment and management of growth and pubertal delay; joint paediatric/adult clinics are used in some settings to improve the handover of patient care.


Effective management of anorexia nervosa in children and adolescents requires close collaboration between paediatric and mental health professionals. Priorities in the early stages are to assess and manage the young person's nutritional status, re-feed as indicated, and open up communication. Key elements include structured mealtimes and close monitoring of intake, weight and electrolytes. In interactions with the young patient, the emphasis is on building trust and avoiding arguments, focusing on what is of interest to the young person, and avoiding coercion. For younger patients, supporting parents is key, working with their strengths. In the absence of a strong evidence base to guide management, the development of locally agreed protocols for paediatric admission and acute care, based on best practice guidance, are advocated. Seeking advice and consultation from specialist centres can be helpful in complex cases.

For further reading in this area, we suggest the following reviews:

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  • Competing interests None

  • Provenance and peer review Commissioned; externally peer reviewed.

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