Eating Disorders

Pica

the repetitive consumption of non-nutritive and non-food substance

mainly affects pregnant women, young children, and people with iron deficiency

may indicate future disordered eating

Rumination Disorder

regurgitation of food which is followed by rechewing and re-swallowing

mainly effects babies and young children

prevalence is hard to tell as nutritional deficits are rare

What did Murray et al. (2018) find about prevalence?

In Swiss children aged 7–13:
1.7% met criteria for pica
3.7% met criteria for rumination disorder
1.1% met criteria for both

Anorexia Nervosa

restriction of energy intake leading to significantly low body weight for age and sex

a distorted perception of body image

intense fear of becoming fat

restrictive and binge/purge subtypes

Bulimia Nervosa

eating a large amount of food with a loss of control followed by compensatory behaviour to prevent weight gain

Binge Eating Disorder

eating rapidly and until uncomfortably full, alongside feelings of disgust and guilt

Night Eating Disorder

repetitive episodes of eating during the night after waking from sleep

Eating Disorder Not Otherwise Specified

a diagnostic category for individuals that do not meet criteria for other eating disorder diagnoses

Human Starvation Study

WW2 prisoners who refused to fight were used to study starvation effects

What physiological changes occur during starvation?

water retention, reduced body temperature, reduced metabolism, lethargy

What psychological changes occur during starvation?

Reduced emotional reactivity and increased fascination with food.

Why might anorexics not experience meal cues from glucose dips?

Blood glucose and insulin are chronically low, potentially blunting normal hunger-triggering dips.

What happens to NPY in anorexia nervosa?

neuropeptide Y (NPY) levels are raised.

Why is raised NPY paradoxical in AN?

NPY stimulates hunger, which may explain food fascination despite food avoidance.

What happens to ghrelin levels in anorexia nervosa?

Ghrelin is elevated and decreases with weight gain, though may remain high in women.

How are satiety hormones affected in anorexia nervosa?

CCK and GLP-1 appear normal.

What is unusual about PYY levels in anorexia nervosa?

PYY appears abnormally elevated despite low food intake.

What might explain elevated PYY in anorexia nervosa?

High levels of physical exercise may increase PYY.

How does dieting affect serotonin function?

Dieting disrupts 5-HT function in women but not men (Goodwin et al., 1987).

Why are SSRIs often ineffective in anorexia nervosa?

Starvation alters serotonin systems, limiting SSRI effectiveness.

When might SSRIs be helpful in AN?

When there is comorbid depression (Luzier et al., 2019).

What is constitutional thinness?

Naturally low BMI with normal fat mass, regular menstruation, and no pathology.

How does CT differ biologically from anorexia nervosa?

CT individuals show no biomarkers of starvation.

How does ghrelin differ in CT women compared to AN?

Ghrelin levels are low in CT women.

What are concordance rates for anorexia nervosa in twins?

~57% in monozygotic twins vs ~3% in dizygotic twins

Why should twin concordance rates be interpreted cautiously?

Identical twins often share environments, clothing, and social pressures.

How many genes have been linked to anorexia nervosa?

Around 25 genes, though functional understanding is limited.

What taste preferences are seen in anorexia nervosa?

Enhanced liking for sugar and aversion to fat (Drewnowski et al., 1990).

What might explain fat aversion in AN?

A conditioned fear and disgust response toward fat.

How is disgust related to AN severity?

Disgust positively correlates with symptom severity.

Which hormones are reduced in anorexia nervosa?

Noradrenaline, sex hormones, thyroid hormones, and oxytocin.

Which hormones are elevated in anorexia nervosa?

beta-endorphin, vasopressin, cortisol, and ACTH.

Do these hormonal changes persist after weight gain?

Most return partially or fully toward normal levels.

Why is amenorrhea important in AN?

Sex hormones and appetite are both regulated by the hypothalamus.

How may hormonal imbalance worsen anorexia nervosa cognitively?

Impaired cognition (e.g. rigid, black-and-white thinking).

What hormone pattern may impair learning and memory in AN?

High vasopressin (AVP) and low oxytocin.

What is the Activity-Based Anorexia (ABA) model?

Restricted food access combined with access to activity (Epling et al., 1983).

What happens to rats in the ABA model?

Increased activity, reduced eating, extreme weight loss, and high mortality.

How does temperature affect ABA outcomes?

Warm environments reduce activity-stress effects.

What effect does leptin have in ABA rats?

Leptin injections prevent excessive weight loss.

What happens to CRF levels in anorexia nervosa?

CRF (corticotropin-releasing factor) is elevated by ~170%.

How does exercise affect CRF?

Exercise further increases CRF.

How does CRF interact with reward systems?

CRF enhances dopaminergic reward pathways.

How does the neuroendocrinological model (Bergh & Sodersten) explain reduced appetite?

Exercise becomes rewarding, food reward is suppressed, appetite decreases.

What is the chronicity model (Keating) of anorexia nervosa?

Dieting and exercise become strongly rewarding despite negative consequences.

What did Keating (2010) propose?

AN alters neural circuitry involved in reward and punishment.

How does this relate to fear conditioning?

Food becomes associated with punishment rather than reward.

What did Murray et al. (2018) find?

Abnormalities in fear circuitry in AN patients.

What is the pre-morbid model (Kaye) of anorexia nervosa?

An imbalance between excessive inhibitory control and reduced reward sensitivity.

What similarities exist between binge eating and substance abuse?

Loss of control and reward-driven behaviour (Hardy & Waller, 1987).

What did Meule (2012) find?

A relationship between food addiction scores and BMI.

What role does serotonin play in BN and BED?

Involved in satiety regulation and mood.

Which SSRI shows benefit in bulimia nervosa?

Fluoxetine (short-term benefit).

What serotonin abnormality is seen in BN?

Reduced 5-HT transporter availability (Kuikka et al., 2001).

How does culture influence eating disorders?

Culture defines standards for self-judgement

What did Crisp (1980) propose about anorexia?

Anorexia is a weight phobia; sufferers aim to achieve a pre-pubertal weight

What did Lasègue suggest about sexuality and AN?

Difficulties with heterosexual relationships may precede anorexia.

What was Freud’s view on anorexia?

He argued that anorexia develops from underdeveloped sexuality

What did post-Freudian theorists suggest about AN and sexuality?

AN may reflect fear of impregnation, fear of sexual abuse, or sexuality more broadly.

What did Beumont (1981) find about sexuality in AN sufferers?

Sexual experiences vary; sexuality is less common at lower BMIs and recovers best when menstruation resumes during treatment.

What did Caslini et al (2016) find about abuse and eating disorders?

Childhood sexual or physical abuse increases the likelihood of developing an eating disorder fourfold

Family theories of anorexia nervosa

the idea that over-protective parenting leads to a desire for control, although it is poorly supported by research

What did Shoebridge and Gowers (2000)?

controlling parenting style in early childhood is associated with later development of anorexia

How common is OCD in anorexia nervosa?

20–30% comorbidity

Is OCD in AN a result of starvation?

Evidence suggests starvation contributes, but recovered individuals may still show OCD traits.