Overview
This lecture introduces the three main eating disorders defined in DSM-5: Anorexia nervosa, Bulimia nervosa and Binge eating disorder. It moves from the diagnostic criteria that distinguish them, to their epidemiology in New Zealand and Australia, to an aetiological model in which sociocultural, family and individual factors combine (no single factor being sufficient), and then to the very different physical, functional and prognostic consequences of each disorder. It closes with the shared treatment principles (psychoeducation, medical monitoring, work on underlying psychological issues, re-establishing normal eating, relapse prevention) and the specific points a doctor needs to hold onto in practice.
Diagnostic criteria (DSM-5)
Anorexia nervosa (Māuiui Whakatiki)
- Persistent restriction of energy intake leading to significantly low body weight, judged in the context of what is minimally expected for age, sex, developmental trajectory and physical health.
- Either an intense fear of gaining weight or of becoming fat, or persistent behaviour that interferes with weight gain, even though weight is already significantly low.
- Disturbance in the way one’s body weight or shape is experienced, undue influence of body shape and weight on self-evaluation, or persistent lack of recognition of the seriousness of the current low body weight.
- Subtypes: restricting type; binge-eating/purging type.
Bulimia nervosa (Pukuruaki)
- Recurrent episodes of binge eating. A binge episode requires both of:
- eating, in a discrete period of time (for example within any 2-hour period), an amount of food definitely larger than most people would eat in a similar period and under similar circumstances;
- a sense of lack of control over eating during the episode (a feeling that one cannot stop eating, or control what or how much one is eating).
- Recurrent inappropriate compensatory behaviour to prevent weight gain: self-induced vomiting, misuse of laxatives, diuretics or other medications, fasting, or excessive exercise.
- The binge eating and the compensatory behaviours both occur, on average, at least once a week for three months.
- Self-evaluation is unduly influenced by body shape and weight.
- The disturbance does not occur exclusively during episodes of anorexia nervosa.
Binge eating disorder
- Recurrent episodes of binge eating, defined exactly as in bulimia nervosa (both the objectively large amount in a discrete period, for example within any 2-hour period, and the sense of loss of control).
- The binge episodes are associated with three or more of the following:
- eating much more rapidly than normal or until uncomfortably full;
- eating large amounts of food when not feeling physically hungry;
- eating alone because of feeling embarrassed by how much one is eating;
- feeling disgusted with oneself, depressed or very guilty afterwards.
- Marked distress regarding the binge eating is present.
- Binge eating occurs, on average, at least once a week for three months.
- Binge eating is not associated with recurrent use of inappropriate compensatory behaviours (this is what separates it from bulimia nervosa).
Epidemiology
Figures are for DSM-IV eating disorders, prevalence from New Zealand and Australian studies averaged across age and sex.
| Median age of onset | Lifetime prevalence | Current (1, 3 or 12 month) | Sociodemographic profile | |
|---|---|---|---|---|
| AN | 17 | 0.6% | < 0.1 to 0.3% | 10x higher in females; higher in young people; no ethnic group differences; no difference by income or education |
| BN | 18 | 1.4% | 0.4 to 0.6% | 4x higher in females; higher in young people; higher in Māori and Pacific; no difference by income or education |
| BED | 21 | 2.0% | 0.6 to 1.0% | 2x higher in females; higher in young people; higher in Māori and Pacific; no difference by income or education |
Key points to scan: onset age rises across AN to BN to BED, prevalence rises in the same order, and the female excess falls in that order (10x, 4x, 2x). Ethnic differences appear for BN and BED but not AN; none of the three differ by income or education.
Aetiology
Sociocultural factors
- Exposure to the pervasive slim ideal of female beauty.
- The slim ideal is concentrated in cultures where food is abundant; in cultures of scarcity the ideal is more likely to be plump.
- Eating disorders increase in non-Western cultures following exposure to Western influences.
- If the slim ideal is internalised by the individual it leads to body dissatisfaction and dieting. Dietary restraint itself can trigger a range of difficulties around food: bingeing, purging, obsessive focus on food.
The restraint pathway, in order:
- Restricting intake
- Deprivation, so that the physical and psychological drive to eat increases
- Eating more than planned, or bingeing
Family factors
Families are often found to be over-protective, controlling and critical, with mother-daughter conflict and the mother’s own struggles with weight or food. These dynamics often follow rather than precede the eating disorder.
Individual factors
- Traumatic or stressful background: abuse, bullying, being teased or criticised about weight, or being reinforced for weight loss.
- Negative emotionality: low mood, high anxiety (especially social anxiety), low self esteem.
- Body dissatisfaction.
- Personality: perfectionism, need for control, obsessive tendencies, and impulsiveness (this last for BN, not AN).
- Emerging evidence of a genetic component to AN.
Aetiology summary
No one factor is a sufficient cause. Rather, several may be necessary in combination, for example internalisation of the slim ideal, body dissatisfaction, and a cluster of personality factors such as low self esteem and perfectionism. AN and BN have been best researched; causal factors for BED are less well understood.
Eating disorders are centrally concerned with problems of identity and control, with some young women becoming invested in achieving the “perfect” body as an existential project, that is, as a way of giving their lives meaning, coherence and emotional fulfilment that are otherwise lacking. (Polivy J and Herman CP, 2002, Causes of Eating Disorders, Ann Rev Psychology.)
Impact and outcomes
| Physical | Impact on role function | Outcomes | |
|---|---|---|---|
| AN | Secondary amenorrhoea and low bone density; cardiorespiratory (hypotension, dysregulated heart rhythm and rate); abnormal renal and liver function; electrolyte disturbances; hair loss and lanugo | Profound, but not admitted by the sufferer. Severe disruption in cognitive and social functioning; major impact on education and development | After 10 years: 30% recovered, 30 to 50% partial recovery, 20 to 40% enduring. High risk of suicide, or mortality from emaciation or physical complications (15% after 20 years) |
| BN | Dental problems from vomiting; electrolyte disturbances (low potassium) from vomiting, laxative and other drug abuse | Not so disruptive of role function; often hidden to observers for years | 50% make a good recovery, 50% partial recovery. Increased risk of chronic physical illnesses |
| BED | All the outcomes associated with obesity | Least disruption in role function of all three eating disorders | Unknown, but probably similar to BN |
Important
AN carries the worst prognosis of the three: only about 30% have recovered at 10 years, and mortality reaches 15% at 20 years from suicide, emaciation or physical complications.
Case stories: physical impact as patients describe it
From the interview excerpts used in the lecture, the lived physical consequences included:
- Severe osteoporosis diagnosed in a young patient, with the fear of fractures and being “in and out of a fracture clinic”.
- Amenorrhoea for years, with blood tests showing hormone levels so low that they indicated a menopausal picture, and the resulting threat to future fertility. Weight gain was framed by the patient as the price of being able to have children.
- Sore throat and a husky voice, tiredness, feeling cold, low energy, inability to concentrate, inability to sleep, general weakness.
- Dental damage: teeth worn down, with root fillings from around age 12, while the teeth still looked white and outwardly fine, so the damage was not visible to others.
Treatment principles
Grouped as presented in the lecture:
- Psychoeducation about the disorder, and about the effects of eating behaviour on thinking, feelings and physical health.
- Medical monitoring as required: electrolytes, renal and cardiac function and so on.
- Target underlying psychological issues
- address body dissatisfaction and low self esteem;
- address other psychological factors as necessary (abuse, anger, anxiety, family issues).
- Monitor weight and eating behaviour using daily records and food diaries.
- Education and CBT focused on re-establishing normal eating
- recognition of the normal amount to eat and the need for weight gain (AN);
- demand feeding / intuitive eating principles, distinguishing physical from emotional hunger (BN and BED);
- medical admission for AN if weight drops below 65 to 75% of expected (BMI 13 to 15).
- Target binge eating and dietary restraint: identify cognitive and emotional triggers to bingeing, and help develop alternative behavioural responses.
- Relapse prevention: identify the factors that maintain the eating pathology or trigger relapse.
Tangata whai ora = person seeking wellness.
Key points for doctors
- AN is relatively rare but can be life threatening. Medical oversight becomes critical as BMI drops.
- BN and BED tend to be hidden. Consider them in people presenting with dental enamel erosion, electrolyte disturbances, GI problems or cardiac irregularities. Note the association with vegetarian and vegan diets.
- Eating disorders require referral to a specialist service, or to a clinical psychologist or psychiatrist plus medical monitoring.
- All eating disorders can have long term medical impact and may take years to resolve.
- They are typically tremendously stressful for families, so rally all available support and services.
Slides with no examinable content
Title slide and copyright notice; the learning outcomes slide; the opening karakia (Karakia Hauora Whakataki) and the closing karakia (He Karakia Tīmatanga me te Whakakapi Kaupapa).
Warning
The “Case stories: aetiology” slide is a photograph or video still only. Any spoken case-story content on aetiology is not present in the PDF and could not be transcribed.
Self-test
- State the three core DSM-5 criteria for anorexia nervosa.
- Name the two subtypes of anorexia nervosa.
- Define a binge-eating episode as DSM-5 does, giving both required components.
- List the inappropriate compensatory behaviours named in the bulimia nervosa criteria.
- State the frequency and duration threshold shared by bulimia nervosa and binge eating disorder.
- Distinguish binge eating disorder from bulimia nervosa on diagnostic criteria.
- List the associated features of which three or more must accompany binge episodes in binge eating disorder.
- Give the median age of onset for AN, BN and BED.
- Give the lifetime prevalence of AN, BN and BED, and state how the female excess differs between them.
- Describe how the three disorders differ by ethnicity, income and education in the New Zealand and Australian data.
- Explain how the slim ideal is thought to lead to disordered eating, and why the ideal varies between cultures of abundance and cultures of scarcity.
- Describe, in order, the steps by which dietary restraint leads to bingeing.
- Describe the family dynamics associated with eating disorders, and state the important caveat about their causal direction.
- List the individual-level aetiological factors, and state which personality factor is specific to BN rather than AN.
- Explain why no single factor is regarded as a sufficient cause of an eating disorder, and state which disorder has the least well understood aetiology.
- Explain what is meant by the “perfect” body being pursued as an existential project.
- List the physical consequences of anorexia nervosa.
- Explain why bulimia nervosa causes dental problems and low potassium.
- Compare the impact on role function across AN, BN and BED.
- Describe the 10-year and 20-year outcome figures for anorexia nervosa.
- State the weight threshold at which medical admission is indicated in anorexia nervosa.
- Distinguish the re-feeding education goal for AN from that for BN and BED.
- List the treatment principles that apply across all three eating disorders.
- A 19-year-old presents to her GP with enamel erosion on her teeth, a persistently husky voice and a potassium of 2.9 mmol/L. Her weight is normal and she volunteers no concerns about eating. Explain what should be suspected and why the presentation was not obvious earlier.
- A 16-year-old with anorexia nervosa has secondary amenorrhoea and is found to have low bone density. Explain the significance of this for her long-term health and why it may motivate engagement with treatment.
- Integrative: explain how the aetiological factors covered in this lecture connect to the treatment principles, that is, which treatment component targets which causal or maintaining factor.
Answers
Reveal answers
- Persistent restriction of energy intake leading to significantly low body weight for age, sex, developmental trajectory and physical health; either intense fear of gaining weight or becoming fat, or persistent behaviour interfering with weight gain despite low weight; disturbance in how body weight or shape is experienced, undue influence of shape and weight on self-evaluation, or persistent lack of recognition of the seriousness of the low weight.
- Restricting type, and binge-eating/purging type.
- Eating, in a discrete period (for example within any 2-hour period), an amount of food definitely larger than most people would eat in a similar period under similar circumstances; and a sense of lack of control over eating during the episode.
- Self-induced vomiting, misuse of laxatives, misuse of diuretics or other medications, fasting, excessive exercise.
- On average at least once a week for three months.
- In binge eating disorder the binge episodes are not associated with recurrent inappropriate compensatory behaviours; BED also requires three or more associated features and marked distress about the bingeing, whereas BN additionally requires that self-evaluation is unduly influenced by shape and weight and that the disturbance does not occur exclusively during episodes of anorexia nervosa.
- Eating much more rapidly than normal or until uncomfortably full; eating large amounts when not physically hungry; eating alone because of embarrassment at how much one is eating; feeling disgusted with oneself, depressed or very guilty afterwards.
- AN 17, BN 18, BED 21.
- Lifetime: AN 0.6%, BN 1.4%, BED 2.0%. The female excess falls across the three: 10x for AN, 4x for BN, 2x for BED.
- AN shows no ethnic group differences; BN and BED are both higher in Māori and Pacific peoples. None of the three differ by income or education. All three are higher in young people.
- Exposure to the pervasive slim ideal of female beauty, if internalised, leads to body dissatisfaction and dieting, and dietary restraint itself can trigger bingeing, purging and an obsessive focus on food. The slim ideal is concentrated in cultures where food is abundant; where food is scarce the ideal is more likely to be plump. Eating disorders increase in non-Western cultures following exposure to Western influences.
- Restricting intake leads to deprivation, in which the physical and psychological drive to eat increases, which leads to eating more than planned or bingeing.
- Families are often over-protective, controlling and critical, with mother-daughter conflict and the mother’s own struggles with weight or food. The caveat is that these dynamics often follow rather than precede the eating disorder.
- Traumatic or stressful background (abuse, bullying, being teased or criticised about weight, or being reinforced for weight loss); negative emotionality (low mood, high anxiety especially social anxiety, low self esteem); body dissatisfaction; personality factors of perfectionism, need for control, obsessive tendencies and impulsiveness; and emerging evidence of a genetic component to AN. Impulsiveness is the factor specific to BN rather than AN.
- Because several factors appear to be necessary in combination rather than any one being sufficient, for example internalisation of the slim ideal plus body dissatisfaction plus a cluster of personality factors such as low self esteem and perfectionism. BED has the least well understood causal factors; AN and BN are the best researched.
- Some young women become invested in achieving the “perfect” body as a way of giving their lives meaning, coherence and emotional fulfilment that are otherwise lacking, reflecting the central role of identity and control in eating disorders.
- Secondary amenorrhoea and low bone density; cardiorespiratory effects (hypotension, dysregulated heart rhythm and rate); abnormal renal and liver function; electrolyte disturbances; hair loss and lanugo.
- Dental problems arise from vomiting, and electrolyte disturbance with low potassium arises from vomiting together with laxative and other drug abuse.
- AN causes profound disruption that the sufferer does not admit to, with severe disruption of cognitive and social functioning and major impact on education and development. BN is not so disruptive and is often hidden from observers for years. BED causes the least disruption to role function of the three.
- At 10 years: 30% recovered, 30 to 50% partial recovery, 20 to 40% enduring illness. There is a high risk of suicide or of mortality from emaciation or physical complications, reaching 15% after 20 years.
- Medical admission for AN if weight drops below 65 to 75% of expected, corresponding to a BMI of 13 to 15.
- For AN the goal is recognition of the normal amount to eat and of the need for weight gain. For BN and BED it is demand feeding or intuitive eating principles, distinguishing physical from emotional hunger.
- Psychoeducation about the disorder and the effects of eating behaviour on thinking, feelings and physical health; medical monitoring as required (electrolytes, renal and cardiac function); targeting underlying psychological issues including body dissatisfaction, low self esteem and factors such as abuse, anger, anxiety and family issues; monitoring weight and eating behaviour with daily records and food diaries; education and CBT to re-establish normal eating; targeting binge eating and dietary restraint by identifying cognitive and emotional triggers and developing alternative behavioural responses; and relapse prevention by identifying maintaining and relapse-triggering factors.
- Bulimia nervosa should be suspected: dental enamel erosion and low potassium are the characteristic physical signs of repeated vomiting and laxative or other drug misuse, and a husky voice and sore throat were reported by patients in the case stories. It was not obvious earlier because BN is typically hidden, weight and role function are often unremarkable, and the condition can remain concealed from observers for years, so doctors need to actively consider it in this pattern of presentation.
- Low bone density is one of the physical consequences of AN alongside secondary amenorrhoea, and carries a long-term risk of fractures. In the case story a patient described being diagnosed with severe osteoporosis and fearing repeated fracture clinic attendance, and separately learning that her hormone levels were so low as to indicate a menopausal picture that threatened her fertility. Both the fracture risk and the wish to have children can act as motivators for accepting weight gain and treatment.
- Psychoeducation and CBT to re-establish normal eating target the restraint-deprivation-binge cycle that dietary restriction sets up. Work on body dissatisfaction and low self esteem targets the internalised slim ideal and negative emotionality identified as aetiological factors. Addressing abuse, anger, anxiety and family issues targets the traumatic or stressful background and the over-protective, controlling and critical family dynamics. Medical monitoring targets the physical consequences of the behaviours rather than their causes. Relapse prevention targets the factors that maintain the eating pathology, reflecting the point that no single cause is sufficient and that several maintaining factors operate together.