Adverse effects of eating disorders in children and adolescents

Eating disorders have serious adverse effects on the health of young people and their families and require urgent and skilled intervention

Dr Fiona McNicholas, Consultant Child & Adolescent Psychiatrist, OLCHC Crumlin and Lucena Clinic, Rathgar; Chair of Child Psychiatry, UCD, OLCHC Crumlin; Lucena Clinic, Rathgar; UCD, Dublin and Mr Diarmuid Lynch, Psychiatry Nursing Studies, Trinity College, Dublin

September 1, 2015

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  • Eating disorders (ED) refers to a range of illnesses characterised by disordered eating patterns and negative thought processes regarding body weight and shape deeply ingrained in the individual. They are debilitating conditions with significant adverse medical, psychological and social impact on the individual and the family. They are notoriously difficult to treat, especially if presentation has been delayed. They have the highest mortality rate of all mental health conditions, causing premature death due to medical complications and suicide. 

    The age of onset is most often in adolescence, with 85% having commenced before 20 years of age. It is therefore imperative that professionals working with children and adolescents are alert to the possibility of an eating disorder and initiate the appropriate treatment without delay. A complacent approach to a young person losing weight (or not gaining the expected weight) is never justified and the family needs to be offered the appropriate support. 

    Although less common (10%), eating disorders presenting pre-pubertally carry more serious risks given the reduced proportion of body fat in children, the rapidity of medical sequelae, and the risk of chronicity. Such cases require even more intensive interventions. This article reviews the presenting features, assessment and treatment. 

    Diagnostic criteria

    Under the DSM-V, ED is classified into four groups:

    • Anorexia nervosa (AN)
    • Bulimia nervosa (BN)
    • Binge eating disorder (BED) 
    • Eating disorder not otherwise specified (EDNOS). 

    Intentional weight loss, body image distortions and fear of fatness are characteristic of anorexia nervosa, but are present to some degree in the other conditions as well (see Table 1).

    Bulimia is an eating disorder characterised by binge eating and compensatory behaviours such as self-induced vomiting, excessive exercise or fasting, and an over evaluation on body weight and shape. 

    In binge eating disorder, which is a new category introduced in the DSM-V, the hallmark is recurrent and frequent episodes of overeating, reinforced by feelings of loss of control and rapid, often secretive eating. In addition there are feelings of intense guilt, shame and depression.1

    The remaining group (EDNOS) describes individuals who have eating and shape related worries and behaviours, but who do not fit into the other three categories listed. It has to be recognised that individuals with EDNOS carry the same clinical risk as the other groups, and just because it does not meet the more stringent criteria set, does not reduce the seriousness of presentation. 

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    Recent estimates suggest that the prevalence of anorexia nervosa is 0.5-1% and bulimia nervosa is 2% in the general population. There has been little empirical study on binge eating disorder; studies in the US suggest a point prevalence of 1-3%, but others argue it is much higher, especially in individuals seeking treatment for obesity where prevalence climbs to 30%. EDNOS is the most common eating disorder group, accounting for three-quarters of all community cases. There is concern that the prevalence is increasing (albeit predominantly in milder cases) and they are presenting at an earlier age. The increase in eating disorders is occurring in a context of an exponential increase in rates of obesity worldwide. We are placed in a precarious position whereby recommendations to improve one group of illnesses (obesity, overweight) may actually be linked with a risk for another (through unhealthy dieting). Reducing the prevalence of obesity and weight issues may have an impact on reducing the prevalence of eating disorders, but needs to be managed sensitively. 

    A Vision for Change2 estimates 200,000 cases of eating disorders with 400 new cases each year, although there has been little systematic study on the prevalence of eating disorders in Ireland. One large cross-sectional study of more than 3,000 adolescents found 11% of respondents scored above the clinical cut off on an eating disorder screen.3 One third of Irish adolescents reported dieting and 29.4% were dissatisfied with their body, suggesting significant weight and shape issues. Additionally, those who reported always to be dieting reported a lower quality of life and perceived themselves to be less popular and less academically able than their peers who did not diet. It is likely that we have the same number of people with an eating disorders as other developed countries. 

    Risk factors

    There is a much higher risk in females compared to males, by a factor of about 10, which lessens in the prepubertal group, where it is 4:1. Other high risk groups include certain professional groups, such as ballet dancers and gymnasts, as well as those with a family history. Being overweight is associated with abnormal eating behaviours also. Studies have found that the timing and the perceived speed of puberty to be a risk factor for the onset of abnormal eating attitudes.4 The media portrayal of body weight and shape has long been debated as having a negative influence on the body image of adolescents and represents a risk for negative eating patterns and thoughts about body image. 

    More than half of Irish adolescent girls (59.1%) felt adversely affected by the media portrayal of body weight and shape, while only one in five males reported this. Other studies have suggested that media influence and pressure to conform to societal norms seem to disproportionately affect vulnerable girls already concerned about their body image and seems to wane with increasing age. 


    The assessment of individuals with an eating disorder requires a focus on the medical and psychological aspects of the disorder. The extent and consequences of malnutrition need to be carefully assessed as even small amounts of weight loss in children can have devastating effects. Weight, height and body mass index (BMI) should be calculated and compared with BMI centile reference charts, along with establishing what has been the highest and lowest weight. A detailed enquiry about dietary intake, exercise levels and compensatory behaviours will allow for the calorie imbalance to be calculated. A physical examination along with a systems review may indicate a need for laboratory investigations such as FBC, U&E and ECG. Physical examination may include pubertal staging and establishing whether amenorrhoea is present. 

    The clinician will identify the core eating psychopathology, such as their concerns regarding weight and shape, the presence of a distorted body image along with more general issues such as a low self-esteem, low mood or ideas of self-harm. These will become the target of the psychotherapeutic interventions. Enquiring about progress and development in other areas, such as at school, with peers and family, will allow for the identification of other risk factors that may need to be addressed in treatment. Collateral histories are often necessary as the young person may be unwilling to share the extent of their difficulties with the clinician. 


    Eating disorders can be very hard to treat due to the egosyntonic nature of the illness, and the need for individuals to have insight into the adverse effects of their illness and have the motivation to want to change. They are often very reluctant to reduce their fixed beliefs about body image, shape and weight. For children and adolescents it is paramount to work with the family and empower the parent to re-feed their ill child. 

    The treatment of eating disorders should be outpatient based, unless the severity and chronicity of the disorder dictate otherwise.5 Irrespective of the setting, the goals of treatment are to help the adolescent restore normal eating patterns, revert to their premorbid weight trajectory, and address the faulty eating psychopathology. 

    The evidenced based treatment for anorexia nervosa in children and adolescents is the family based treatment (FBT) model also known as the Maudsley Model.6 The first of the three phases consists of providing information about the medical and psychological negative effects of the illness to the whole family, creating a grave scene and reminding them of the real possibility of death if the young person does not start to eat and regain weight. The responsibility of feeding is given to the parents and they are encouraged to take charge of planning, serving and ensuring adequate nutrition for their child. 

    Only with consistent weekly weight gain of about 0.5-1kg per week, will the treatment move to phase two, where the young person gradually takes more responsibility for their own nutrition and health, and begins to resume normal activities such as sports, exercise and hobbies while the focus continues around weight restoration. 

    The last phase occurs when the eating psychopathology has diminished significantly, and weight has been adequately restored, thus allowing other adolescent developmental issues to be considered, such as independence, autonomy, family conflicts and relationship difficulties. The family is educated about relapse, early recognition and advised on how to manage it. The FBT model is an outpatient based approach with sessions occurring weekly initially, and moving to one to three monthly, totalling about 20 sessions.

    Depending on the physical health of the adolescent, an inpatient admission to a general medical/paediatric hospital may be necessary for medical stabilisation, careful feeding and weight gain, prior to OPD treatment. At times naso-gastric feeding is required, and brings up difficult consent issues, along with a real risk of re-feeding syndrome if carried out too quickly. 

    Due to the complex interplay of bio-psycho-social aspects of eating disorders in adolescents, the optimal management of the condition involves the expertise and dedication of a multidisciplinary team, including a dietitian, with experience in the management of eating disorders for optimal results.

    The treatment of bulimia nervosa and binge eating disorder follows a cognitive behavioural therapy (CBT) approach, which is also useful in older patients with anorexia nervosa. The eating attitudes and behaviours that maintain the eating disorder are identified and challenged, a normal pattern of eating (typically three meals and three snacks) is advocated, and a behavioural approach used to stop bingeing, fasting and purging. 

    Interpersonal psychotherapy may also be considered as an alternative to CBT, where there are significant interpersonal issues. High dose fluoxetine (60mg) has been found to be useful in some patients with bulimia nervosa, as has the use of antidepressants associated with comorbid depression. 

    Support organisations such as Bodywhys in Ireland offer invaluable support and advice to individuals, carers and professionals, and should be a standard part of all interventions ( 


    As stated at the outset, eating disorders are recognised to have one of the highest mortality rates of any mental health disorder, and early intervention significantly improves the outcome. Good prognostic factors include early age of onset (before 18 years), a short duration of illness before treatment, fewer associated comorbidities, and better family functioning. About half of people will recover from their illness, although it may take up to five years, and for a significant group it represents a chronic disorder with periods of relapse at times of stress. Helping the young person identify these stressors and managing them in ways other than not eating is a fundamental part of treatment. 


    Eating disorders are serious mental health disorders which have their onset and presentation in childhood. They run the risk of having serious adverse effects on the young person and their family and require urgent and skilled interventions. Complacency about intentional weight loss, or a misinterpretation of body image dissatisfaction as the ‘normal discontent’ of westernised females has no place in managing these very vulnerable individuals. All clinicians in contact with children should be aware of the warning signs and make the appropriate referrals for treatment. 

    1. Diagnostic and Statistical Manual of Mental Disorders, 5th Edition: May 18, 2013 American Psychiatric Association 
    2. A Vision for Change, Report of the Expert Group on Mental Health Policy Department of Health and Children Publications, 2006
    3. McNicholas F, Lydon A, Lennon R, Dooley B. Eating concerns and media influences in an Irish adolescent context. Eur Eat Disord Rev 2009 May; 17(3):208-13
    4. McNicholas F, Dooley B, McNamara N, Lennon R. The impact of self-reported pubertal status and pubertal timing on disordered eating in Irish adolescents. Eur Eat Disord Rev 2012 Sep; 20(5): 355-62.
    5. The National Institute for Health and Clinical Excellence (NICE). Eating Disorders. Core interventions in the treatment and management of anorexia nervosa, bulimia nervosa and related eating disorders. 2004
    6. Lock J, Le Grange D, Agras WS, Dare C. Treatment manual for anorexia nervosa: A family-based approach. New York, NY: Guilford Press, 2001
    © Medmedia Publications/Hospital Doctor of Ireland 2015