2 Neuroscience2.11 Integrated neurobiology of syndromes and states
2.11.16 Neurobiology of eating disorders
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Written by Resident Doctor Committee · Published
New in the 2027 syllabus
The College added this topic for exams from January 2027.
How the systems fit together
No single brain centre drives eating. The hypothalamus senses the body's energy balance. The brain combines these signals with reward, interoception (sensing the body's internal state), learning and cognitive control.
Insular networks help sense internal bodily states.
Striatal and frontal systems help with reward learning, habits and control of behaviour.
Genetics and imaging
Anorexia nervosa has genetic associations with both psychiatric and metabolic traits. This suggests that several mechanisms interact. It does not point to a single metabolic cause.
Imaging studies report circuit differences across patient groups. These may reflect a predisposition, effects of the illness, starvation or recovery. Cross-sectional imaging (scans taken at a single point in time) cannot reliably tell these apart.
Effects of restriction and of bingeing and purging
Process | Biological consequence |
|---|---|
Prolonged energy deficit | Leptin falls and reproductive signalling is suppressed |
Adaptation to starvation | Changes in thyroid signalling, autonomic function and energy expenditure |
Malnutrition | Poorer concentration and altered emotional processing |
Repeated vomiting or other purging | Fluid and electrolyte disturbance, which can carry a risk of arrhythmia |
Nutritional restoration after marked depletion | Insulin drives shifts in electrolytes, which can cause refeeding complications |
Binge eating means losing control over eating. Hunger or body weight alone cannot explain it.
Interpreting results and assessing the patient
Hormone levels often change with nutritional state. An abnormal result may be a consequence of the illness rather than what started it.
Weight restoration can improve some cognitive and physiological abnormalities. Psychological and behavioural difficulties may still need continuing treatment.
Assessment therefore brings together physical state, eating behaviour, cognition and social context. Do not treat a brain scan or a blood marker as diagnostic.