Sarah Elder, Dietitian

By Sarah Elder, Registered Dietitian

Eating disorders are a serious mental health illness that are thought to effect 1.25 million people in the UK with 19% being diagnosed with bulimia nervosa. You cannot tell if someone is suffering from an eating disorder from their weight or how they look. Currently it is thought that the average duration of the illness is 5 years, however, early identification and treatment can lead to a quicker recovery. Let’s investigate the role of Dietitian in the treatment of bulimia nervosa.

What is bulimia nervosa and how is it diagnosed?

Bulimia nervosa is diagnosed by a trained individual using the diagnostic manuals; The Diagnostic and Statistical Manual of Mental Illnesses edition 5 (DSM V) or  International Classification of Diseases 11th revision (ICD 11). Someone living with bulimia nervosa will be preoccupied with weight and shape which strongly influences self-evaluation. They will engage in binge episodes followed by purging episodes, with the binge episodes being frequent and re-occurring. They are followed by repeated compensatory behaviours that prevent weight gain such as self-induced vomiting, exercise or misuse of laxatives or diuretics.

If the criteria are not met someone may be diagnosed with other specified feeding or eating disorder (OSFED).

The ICD-11 sates that bulimia nervosa is characterised by: 

  • Frequent, recurrent episodes of binge eating (e.g., once a week or more over a period of at least one month)
  • A binge eating episode is a distinct period of time during which the individual experiences a subjective loss of control over eating, eating notably more or differently than usual, and feels unable to stop eating or limit the type or amount of food eaten.
  • Binge eating is accompanied by repeated inappropriate compensatory behaviours aimed at preventing weight gain (e.g., self-induced vomiting, misuse of laxatives or enemas, strenuous exercise).
  • The individual is preoccupied with body shape or weight, which strongly influences self-evaluation.
  • The individual is not significantly underweight and therefore does not meet the diagnostic requirements of Anorexia Nervosa.

Taken from International Classification of Diseases 11th Revision The global standard for diagnostic health information (ICD 11).

What is a binge and how is it different to overeating?
A binge eating episode is when someone eats substantially more food than normal or different food to normal. This will happen over a district period of time and they will feel a loss of control over how much they have eaten. This could be at set time or irregular times through the day or week. They will feel unable to stop or limit the amount they are eating which can result in feeling uncomfortably full and in pain. This pattern of eating will be accompanied by a great deal of distress and will have a significant impact upon areas of their life such as education, occupation, relationships, and other important areas of functioning.

What are the physical and nutritional impacts of bulimia nervosa?
Bulimia is associated with serious medical complications and reduction of quality of life due to frequency and mode of purging behaviours. Clients with bulimia nervosa are not typically underweight but can be malnourished. In those clients who are of a low body weight additional medical complications are associated with starvation.  Purging behaviours are associated with electrolyte disturbances; dehydration and physical damage to the body.

Purging dramatically effects changes in electrolytes levels, most specifically potassium and hydration status if effected. Dental decay, bleeding from upper GI tract, acid reflux,  gastro-oesophageal reflux disease (GORD) and reverse peristalsis (the reverse of the involuntary smooth muscle contractions of peristalsis). Visually you may see swollen parotid and salivary glands. Laxative abuse can induce bowel movements and can lead to nausea and cramps.

Are people diagnosed with bulimia nervosa at risk of developing re-feeding syndrome?

Vomiting and laxative abuse are risk factors for the development of re-feeding syndrome as they can contribute to low levels of electrolytes. Current advice from the MEED guidance is based on research from Anorexia Nervosa, however, it clearly states that careful nutritional care and intervention is needed for anyone with an eating disorder that is at risk of developing re-feeding syndrome.  Risk factors include; extremely low weight, prolonged low intake, deranged baseline electrolytes, low white cell count or at risk of thiamine deficiency or medical complications such as pneumonia, cardiac disease, liver disease or alcohol misuse. Anyone at risk of developing re-feeding syndrome need to be assessed as per Medical Emergencies in Eating Disorders guidance (MEED) and the treatment plan developed as part of a multidisciplinary team (MDT).

Clinical and laboratory features of established refeeding syndrome can include:

  • Severely low electrolyte concentrations
  • Potassium <2.5mmol/l
  • Phosphate <0.32mmol/l
  • Magnesium <0.5mmol/l
  • Peripheral oedema (soft-tissue swelling due to accumulation of interstitial fluid)
  • Acute circulatory fluid overload
  • Disturbance to organ functions (e.g. respiratory failure, cardiac failure, pulmonary oedema, raised liver transaminases)

(Royal College of Psychiatry 2022 and Rio et al., 2013)

What are the key guidelines on nutrition and bulimia nervosa that we should be following?

Nice guidelines for Eating Disorders (NG-69) suggests that there is evidence to support adults to recover from bulimia nervosa using Guided Self-Help (GSH) and for children the use of bulimia nervosa focused family therapy (FT-AN) is advised first line. Cognitive Behavioural therapy for eating disorders (CBT-ED) should be considered second line. Medication should not be offered as sole treatment for bulimia nervosa.

It is suggested that individual CBT‑ED for adults with bulimia nervosa should address extreme dietary restraint and the tendency to binge eat in response to difficult thoughts and feelings. FT-BN is to include information about dieting and the adverse effect of attempting to control weight. Working as part of a multidisciplinary team (MDT) and receiving appropriate supervision is key to safe working and best outcome for clients.

Tell me more about Dietitians and their role in delivering guided self help. . .

Guided Self Help (GSH) is psychological therapy that is based on a mix of CBT (cognitive behavioural therapy) and includes elements of DBT (dialectical behaviour therapy), mindfulness and motivational interviewing (MI). It consists of a manual that the client works through, and they are supported by a guide who helps them to become their own therapist. Nutrition topics are a key part of guided self-help manuals. Traviss et al 2013 has found that Dietitians have key skills and qualities needed by a guide to allow high quality delivery of GSH.

What is the role of the Dietitian in nutritional treatment?
The Dietitian can play a part within the MDT by offering nutritional assessment and nutritional counselling, however, the relationship between the Dietitian and the client is thought to play a large part in the treatment success.  In a review in 2019 the objective of dietary interventions and treatment was to support clients with low body weight to restore weight and establish a regular diet. In all clients independent of weight it was suggested that eating behaviours could be stabilised to improve any nutritional deficiencies, increase variety of food choices and meet balanced eating recommendations.

International studies suggest that nutritional assessment should consider assessment using the Dietetic Model and Process as set out by the Dietetic Association in 2020 and dietary assessment should assess the following aspects:

  • Current intake and excess intake (e.g. alcohol, nutritional supplements, herbal supplements containing laxatives, convenience foods)
  • Insufficient intake of nutrition (examples include; nutrient deficiencies, missing food groups and interest in food)
  • Current intake and how it differs from nutritional recommendations
  • Food allergies and intolerances
  • Knowledge of nutrition and awareness of health implications (examples include disordered beliefs about the effect of specific foods or nutrients, inability to apply food and nutrition information to change behaviour)
  • Culinary skills (e.g. ability to plan, shop and prepare meals)
  • Physical activity
  • Current food availability and insecurity

Nutritional interventions to support clients with bulimia nervosa can be offered as part of the MDT and include support with meal planning and advice on normal eating to reduce the use of diet products, inappropriate utensils and reliance measuring or weighing food. Nutritional education is a key skill of Dietitians and topics such as metabolism, nutritional requirements, and information about specific nutrients as well as information on hunger and satiety are useful. Psychoeducation around the effects of starvation, consequences of binge eating and compensatory behaviours can be offered when clients request support for this.  Advice should be offered on how to reduce and stopping weight loss behaviours.  Strategies such as goal setting, food exposure hierarchy and self-monitoring can be used to support behavioural change as well as support around practical food preparation skills and social eating skills.

Specific changes to dietary intake should focus on meeting adequate intake of the food groups and fluid as well as fat-soluble vitamins and essential fatty acids. Calcium needs should be discussed in relation to supporting bone health if this has been identified as a risk. A discussion on the reliance of filler foods such as diet soft drinks and caffeinated beverages should form part of the sessions offered.

So what are our key points for practice?

Bulimia nervosa is a serious mental health illness that is characterised by episodes of bingeing following by purging such as self-induced vomiting, laxative abuse or misuse of diuretics. Nutritional risks in this client group include; re-feeding syndrome, electrolytes disturbances, gastrointestinal changes and dehydration. Dietetic interventions include meeting nutritional needs, meal planning, reduction of compensatory behaviours and educating on accurate nutritional messages through nutritional counselling to support behaviour change. Working as part of an MDT and having regular supervision and training is key when working with clients with eating disorders allowing for safe and effective support.

References PDF




ARFID: Nutritional Management


Eating Disorders in the Community: Spotting the Warning Signs