People with anorexia nervosa maintain a low body weight as a result of a preoccupation with weight, construed as either a fear of fatness or a pursuit of thinness
Aetiology
Higher incidence in females
Highest incidence 15-19 years
Clinical features
History
Preoccupation with food and calories
Starvation via restricting intake, purging (through induced emesis, diuretic or laxative abuse) or excessive exercise
Poor insight
Overvalued, intrusive obsession with weight, shape and fear of becoming fat
Weight/calorie goals in mind regardless of their impact on physical health
Personality traits
Common traits: anxious, obsessional, risk avoidant, may avoid independence
Relationships often isolated, usually conflict-avoidant
Examination
BMI <17.5 kg/m2 (contrast with bulimia nervosa, where there may be many similar features, but the BMI is normal, a key distinguishing feature)