Lecture 8: Eating Disorders

homeostasis

-internal balance mechanism

-balancing hunger and satiety

-keeps us eating evenly and diversely

-ensures we are well nourished 

impacts on hunger (issues with homeostasis)

-genetics

-learning

-social learning

impacts on satiety (issues with homeostasis)

-social pressures

-food industry

-’toxic environment’ 

eating disorders definition 

-a persistent disturbance of eating behaviour or behaviour intended to control weight

-significantly impairs health or psychosocial functioning 

issues with eating disorders definition

-always an issue of ‘eye in the beholder’

-where do exercisers, models, gymnasts and ballerinas fit

-it is purely about weight?

-gender, age, ethnicity

-younger cases

-eating and feeding disorders

-avoidance/restrictive food intake disorder

issues with eating disorder diagnoses

-diagnoses change over time → suggests we do not fully understand 

-ICD tends to follow DSM 

-stereotypes are wrong → only about 15% of cases are underweight 

body mass index (BMI)

weight in kg / height in m²

-for most people will be in range 19-25 (healthy)

-not biologically determined → varies with factors such as anonymity

-not very meaningful for younger people → use expected weight for height, adjusted for age

• <85% underweight, <70% dangerously underweight

overweight BMI

-overweight = BMI > 25

-obese = BMI > 30

anorexia nervosa

-persistent restriction of energy intake leading to significantly low body weight

-in 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 significantly low body weight

diagnostic criteria for anorexia nervosa

-disturbance in the way one’s body weight or shape is experienced

-or 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, binge-eating/purging type

using weight (issues with anorexia definition)

-people differ in their set point for weight → so is weight/BMI a helpful tool for definition 

-various suggestions for weight and BMI: 

• at least 15% below expected weight for height 

• BMI < 17.5 

• adjust for specific ethnic groups 

• all have fundamental conceptual and practical problems 

athletes (issues with anorexia definition)

-athletes tend to count as more overweight → more muscle 

-ballerina and gymnasts sanctioned to be underweight 

extreme examples of low weight 

-weight is not a sure-fire indicator of anorexia 

-hard to tell from visuals who has low BMI 

-better at spotting extreme examples 

-especially where we have seen the before and after states 

-or where weight loss is way beyond a BMI of 17.5 

-but might be starvation for other reasons 

Dutch famine (starvation for other reasons)

-famine in German-occupied Netherlands

-densely populated western provinces during a harsh winter near end of WWII

bulimia nervosa

-recurrent episodes of binge eating

-eating, in a discrete period of time more than most people would eat during a similar period and under similar circumstances

-sense of lack of control, over-eating during the episode

-recurrent inappropriate compensatory behaviour in order to prevent weight gain

-self-induced vomiting, misuse of laxatives, diuretics, or other medications, fasting or excessive exercise

diagnostic criteria for bulimia nervosa

-binges and compensatory behaviours both occur, on average, at least once a weak for three months

-self-evaluation unduly influenced by body shape/weight

-does not occur excessively during episodes of anorexia nervosa

defining a binge (issues with bulimia definition)

• subjective → loss of control 

• objective → loss of control + excessive intake 

• over 2000/3000 calories 

defining compensatory behaviours (issues with bulimia definition)

-is vomiting always self-induced? 

-is exercise for health or to control weight?

-how often do the behaviours have to happen? → keep changing the number needed for diagnosis 

binge-eating disorder

-recurrent episodes of binge eating

-eating, in a discrete period of time more than most people would eat during a similar period and under similar circumstances

-a sense of lack of control, over-eating during the episode

binge-eating episodes

-eating much more rapidly than normal

-eating until feeling 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 afterward

binge-eating disorder diagnostic criteria

-binge-eating episodes 

-marked distress regarding binge eating 

-no purging or compensatory behaviours 

issues with binge-eating definition

-defining a binge

-recent formal diagnosis → still debate about definitions

-need to understand the motivation for bringing in this category → genuine distress and need for treatment

• but also access to insurance funding for clinicians as a way of treating a lot of overweight/obese patients

other specified feeding and eating disorders (OSFED)

-known as atypical cases

-used to be known as eating disorder not otherwise specified (EDNOS)

-present with many of the symptoms of other eating disorders → but do not meet the full criteria for diagnosis

-e.g., purging disorder and night eating syndrome

reasons for introducing OSFED

-real problems that would benefit from help

-insurance industry will only pay out for diagnosed cases

-people with eating disorders are highly variable and do not neatly fit diagnoses

atypical anorexia nervosa (OSFED)

-despite significant weight loss, the individual’s weight is within or above the normal range

atypical bulimia nervosa (OSFED)

-low frequency and/or limited duration

atypical binge-eating disorder (OSFED)

-low frequency and/or limited duration

avoidant/restrictive food intake disorder (ARFID)

-primarily found in children and young people

-disturbance in eating or feeding:

• substantial weight loss/lack of weight gain

• nutritional deficiency

• dependence on supplements

-absence of typical beliefs about food or fear of weight gain

-effective treatments are primarily behavioural → focus on anxiety/exposure 

sensory-based avoidance (AFRID subtype) 

-refused food intake based on smell, texture, colour, brand, presentation 

lack of interest (AFRID subtype) 

-in consuming the food, or tolerating it nearby

fear-evoking (AFRID subtype) 

-food associated with fear-evoking stimuli

-developed through a learned history

Fairburn - need for diagnoses

-diagnosis of specific eating disorder are not very helpful:

• 40-50% of cases do not fit neatly into diagnoses

• atypical cases are the largest single group

• many fail to stay in one diagnosis

• doesn’t indicate the best treatment

transdiagnostic model (Fairburn) 

-shift away from rigid diagnoses 

co-occurring psychological problems

-anxiety disorders

-depressed mood

-complex emotional and relational needs → anxiety/impulsivity based

-alcohol use and substance use → higher risk

high mortality rates

-due to a range of problems: 

• cardiac complications 

• muscular weakness 

• osteoporosis 

• liver damage 

• oesophageal tearing 

• fainting 

incidence of eating disorders

-number of new cases in a set window of time

-slow onset, usually secretive and slow diagnosis means incidence is hard to calculate

prevalence

• point prevalence → number of current cases

• annual prevalence → number of people who have had the problem over the past year

• lifetime prevalence → case over lifetime

prevalence rates of EDs

-depends on assumptions made

-Beat estimated about 750,000 cases in UK

-Butterfly Foundation estimated a much higher rate in Australia

-but most focus on the young, female population

lifetime prevalence rates

• anorexia → 4% women, 0.3% men

• bulimia → 3% women, 1% men

• binge eating → 2.8% women, 1% men

-OSFED has highest lifetime prevalence

-in Western cultures prevalence of binge eating up to 6.1% women and 0.7% men

medical records reviews

-struggle to tell us about the number of cases → only tell us how many cases were ‘spotted’

-GPs are not perfect at spotting cases

• even where the person is very underweight

• especially not if the person isn’t young, white and female

-spikes in number of cases is not about new cases but rather about awareness being raised

impact of westernisation 

-not clear that westernisation is related to increasing identification and prevalence

-likely due to body image and control issues 

Curacao study (impact of westernisation)

-overall incidence of anorexia much lower than in the affluent societies of US and Europe

-sociocultural factors associated with differential incidence rates

-shows more cases among non-whites in recent years

Fiji study (impact of westernisation)

-clear link to the introduction of western media 

-both TV and social-network based exposure associated with eating pathology → independent of other cultural exposures 

sociocultural causal factors

-early parenting, abuse, bullying, emotional invalidation, childhood obesity, parental mood/eating, puberty, childhood anxiety

-probably some of them are relevant

issues with sociocultural causal factors

-weak causal evidence 

-lack longitudinal data 

-selective sampling 

-risk of selective memory and when asking 

-risk of misinterpreting associations 

neurobiological causal factors 

-hypotheses are much more common than actual evidence 

-some evidence for role of genetics → do not know responsible genes 

-but are these genes responsible for EDs directly or do they cause risk factors such as: 

• perfectionism 

• serotonin mechanisms that predispose impulsivity or compulsivity 

neural mechanisms

-some have proposed hypothalamic damage preventing hunger

-however anorexia patients report lots of hunger → but resist this urge

issues with neurobiological causal factors

-issue of causality → does biology cause ED or does ED cause messed-up biology 

-starvation effects seem to go away when the person eats: mood improves, cognitive deficits improve, no desire to socially isolate and do more activity 

cognitive patterns (maintaining eating disorders)

• low self esteem

• negative self-attribution

• perfectionism

-each has a self-maintaining cycle

broken cognitive link (main cognitive belief system)

-broken cognitive link between eating and weight

-drives restriction, then binging, then gaining weight → repeats

strong dissonance (broken cognitive link)

-assumption that even small amount of eating will lead to disproportionate weight gain

-assumption that any weight gain will be uncontrollable and unstoppable

-therapeutic task helps rebuild the link

overvaluation (main cognitive belief system)

-overvaluation of appearance and weight as defining ourselves as being acceptable people 

-placing self-worth in appearance and weight 

safety behaviours

-behaviours that calm us temporarily when we are anxious

• binge eating

• restricting

• body avoidance/checking

• exercise

• purging

-but long-term consequence is feeling worse

-so do behaviour again → forms a cycle

emotional factors 

-anxiety is the biggest emotional maintaining and triggering emotion for eating problems 

-particularly related to safety behaviours 

-see impact of other emotions: anger, loneliness, boredom

-depression is more of a consequence than a cause 

perceptual factors

-perceptual distortions in eating disorders

-individuals with an eating disorder see selves as 35-30% larger than they are

• in non-clinical women around 10-15% overestimate

-about how we overestimate the size of valued objects

-can misperceive weight

social factors

-social pressure to be thin is widespread in western culture

-evidence that reading fashion magazines worsens body image and self-esteem

-more aggressive social media:

• image-based sites encouraging comparison and self-criticism

• ‘thinspiration’/pro-AN websites

formulating cases 

-way of understanding factors that contribute to maintaining an ED → not diagnostic

-allows for the way that individuals differ in their history and their potential causal and maintaining factors

-assumes some core functions and processes that underpin most cases

ABC model (formulating cases)

-linking antecedents, behaviours and consequences

-focus on feedback loops that maintain the problem

binge - formulating behaviours 

-completed with the individual to normalise what they do when they binge-eat 

-helps to learn to identify risk 

-identifies triggers → what happens in period before binge 

-identifies particular risk times 

-setting conditions: 

• how much a person ate that day → if restricting then more likely to engage in a binge 

• cognitive frame of mind → disinhibition or permissive cognitions, alcohol, disassociation 

formulating cases of eating disorders

-different models exist → have varying levels of evidence and complexity

-needs to be parsimonious to be useful

-Fairburn model is complex and has weak evidence

functional analytic model (formulating cases of eating disorders)

-central role of control

-stress is maintenance element

-past experience/core beliefs leads to perfectionism and low self-esteem

-causes a need for control

-leads to restriction which causes negative emotional states

-causes starvation which leads to fear of loss of control and cycle repeats

-can also lead to positive view of the world which also maintains cycle