Eating disorders are fairly common, anorexia can be potentially serious and cause fatality. The information below considers the basics, the book above will details the initial education relating to body physiology, an essential initial step in the treatment. 

Normal physiology in teenage girls (anorexia disrupts this significantly)

  • Puberty – occurs over a range of 4-5 years
  • Peak height velocity for girls is at 11.5 on average (growing on average 9 cm per year).
  • Menarche is one of the last events of puberty.
  • Puberty / Growth Spurts - Growth is especially rapid during puberty, with girls’ mean weight increasing from 34 kg at age 11 years to 48 kg at age 13 years; this represents a 41% increase in 2 years.
  • The estimated average energy requirement in the UK for healthy girls aged 11–18 years ranges from 1845 kcal to 2110 kcal

Clinical features and physiological features of anorexia:

  • Starts as adolescent preoccupation with diet / weight
  • Weighing several times a day
  • Downward setting of weight goals
  • Growing list of forbidden food
  • Egosyntonic thinking (person does not think there is a problem)
  • Self-induced weight loss by - Skipping meals, avoidance of "fattening foods", self-induced vomiting / purging, excessive exercise, use of appetite suppressants, diuretics and Laxatives.
  • There is body-image distortion with an intrusive dread of fatness - the patient imposes a low weight threshold on himself or herself.
  • Presence or absence of binges
  • Co-morbid emotional disorders
  • Body weight 15% below that expected weight for height
  • Pre-pubertal patients fail to make the expected weight gain, delayed or arrested puberty.
  • A widespread endocrine disorder manifest as amenorrhoea

For details on adverse effects of different body parts go to the presentation

BMI is not helpful in Children and Adolescents: The average BMI in childhood changes substantially with age. At birth = 13 kg/m2, increases to 17 at age 1, decreases to 15.5 at age 6, then increases to 21 at age 20. It hence unreliable as a sole clinical marker in young people. Other factors also make it unreliable, these are detailed on the slide presentation.


  • Motivational interviewing / Education
  • Re-feeding syndrome – oedema (usually normal), cardiac and respiratory failure, delirium & fits.
  • Nutritional supplements & monitoring of bloods
  • Dietetics - Daily intake initially may be ~ 800 (start low in cases with high risk of re-feeding syndrome) to 1800 cal but would have to go up to 3000 cal / day - depends also on level of physical activity, to account for expected growth, a positive energy balance is needed. A weekly weight gain of 0.5 to 1 kg in inpatient settings and 0.5 kg in outpatient settings should be an aim of treatment.
  • Target weights need changes if growth spurt happens during re-feeding.
  • Family Based Therapy - mobilise family resources to improve intake first before treating family dysfunction.
  • Cognitive Behaviour Therapy enhanced for Eating Disorders and other approaches Analytical Therapy / Interpersonal Therapy / CBT (more robust evidence for BN)
  • Medication – symptomatic (medical) and for psychiatric co-morbidity only (anecdotal use of Olanzapine may help with cognitive rigidity; anti-depressants for severe underlying or co-occurring anxiety or mood problems).

Dr A Joglekar

Dr Joglekar's short book on Understanding Anorexia using knowledge and information imparted in secondary school science lessons can be downloaded as a Kindle e-book via the link below.