THMC Mental Health & Innovation Centre
ADHD and Dementia Assessment
緻安精神健康醫療創新中心
Mental Health Clinic Specializing
in ADHD and Mood Disorders
for Children and Adults
Open as Usual on Saturday Afternoons
飲食失調
(神經性厭食和貪食症)
Eating Disorders (Anorexia and Bulimia Nervosa)
There are two types of eating disorders. Anorexia Nervosa refers to the condition where a person has body image disturbance and always tries to lose weight through extreme diet restriction and excessive exercise. As a result, the Body Mass Index (BMI) drops to a dangerous level, potentially leading to medical complications. In contrast, Bulimia Nervosa is characterized by frequent binge eating and results in purging behaviour (e.g self-induced vomiting). People with Bulimia Nervosa usually have normal or high BMI.
A case of anorexia nervosa
Rachael is a 17-year-old Secondary 5 student. Last year, she weighed about 58 kg. A year later, she weighed 42 kg and her periods had stopped. She is now preoccupied with two things – getting top grades on the DSE exam and controlling her weight.
What are the diagnostic criteria for anorexia nervosa?
-
There is weight loss leading to a body weight of at least 15 percent below the normal or expected weight for height or age or a Body Mass Index (BMI) less than 17.
-
The weight loss is self-induced by avoiding food and healthy diets or excessive exercises.
-
There is a a self-perception of being too fat with an overwhelming dread of fatness. This leads to a self-imposed low weight threshold.
-
There is a widespread hormonal disturbance which may lead to amenorrhoea (lack of menstruation in women).
How do family doctors/psychiatrists treat anorexia nervosa?
When family doctors or psychiatrists treat anorexia nervosa, they work with a dietitian to develop a safe dietary amount. Patients need to eat slowly and gradually. The patients need to go through a series of blood tests and ECG.
For patients with anorexia nervosa, since the brain is in a long-term state of malnutrition, affecting thought and logic, psychiatrists may also prescribe medications that will increase appetite and normalize their thoughts.
A case of bulimia nervosa
Wendy is a 25-year-old single mother. She felt abandoned by her boyfriend when he refused to have meals with her. She felt unhappy, hunger, preoccupied with food and irritable. She stuffed herself with food until she could physically eat no more. Then she felt guilty. She made herself vomit. She binges several times a week.
What are the diagnostic criteria for bulimia nervosa?
-
There are recurrent episodes of overeating at least twice a week over a period of 3 months. Large amounts of food are consumed in short periods of time.
-
There is a persistent preoccupation with eating, and a strong desire or sense of compulsion to eat.
-
The patient attempts to counteract the fattening effects of food by self-induced vomiting and purging.
-
Their body weight may be normal or overweight.
How do family doctors/psychiatrists treat bulimia nervosa?
Family doctors or psychiatrists usually prescribe antidepressants to stabilize mood and reduce impulsive binge eating. Cognitive behavioral therapy (CBT) can help patients to reduce binge eating.
Source:
Academic papers in which Dr Roger Ho is one of the co-authors
Basant Puri, Anne Hall and Roger Ho Revision Notes in Psychiatry (3rd edition) CRC Press (Taylor and Francis): New York (An 848-page book) ISBN-10: 1444170139.