anorexia - Loss of appetite
anorexia nervosa - A disorder characterized by a disturbed sense of body image, a morbid fear of obesity, a refusal to maintain a minimally normal body weight, and, in women, amenorrhea (absence of menstrual periods).
bulimia - Insatiable appetite
bulimia nervosa - A disorder characterized by recurrent (at least twice a week) episodes of binge eating during which the patient consumes large amounts of food and feels unable to stop eating, followed by inappropriate compensatory efforts to avoid weight gain, such as self-induced vomiting, laxative or diuretic abuse, vigorous exercise, or fasting.
The incorrect usage of medical terminology regarding eating disorders has played a significant role in blurring the distinction between mental illness and physical illness for the general public. Ask any person on the street what "anorexia" is and they'll say, "oh, that's where girls starve themselves", or "isn't that an obsessive-compulsive disorder?" Many laypeople, as well as many eating disorder counsellors and therapists do not seem to be aware that "anorexia" is defined as a loss of appetite, and can be caused by a large number of medical disorders, including influenza, infections, inflammation, chronic pain, a multitude of digestive tract disorders, anxiety, depression, poisoning and even medications. Most recent books on eating disorders use the term "anorexia" loosely and imply Anorexia Nervosa. This may seem a trite detail, but it is not. This misuse of the word has misled millions of people into thinking that all anorexia, and the subsequent malnutrition it can cause, are a result of mental illness, namely, anorexia nervosa.
It is pertinent to note that as a result of two decades of these semantic errors, even the latest version of the Oxford Dictionary of Current English erroneously calls "anorexia" a psychological disorder.
Most people will label a malnourished person living in a first-world country "anorexic", implying Anorexia Nervosa. Few realize that a person with cancer, hepatitis, gastric ulcer, gallstones, or Chron's disease can develop anorexia and subsequently suffer extreme malnutrition, and appear physically the same as someone with Anorexia Nervosa. A seriously malnourished girl will develop lanugo hair, bradycardia, amenorrhea, dry skin, hypothermia, and an emaciated appearance regardless of whether her anorexia is induced by physical illness or mental illness (many physicians will interpret the presence of these symptoms as evidence of AN, when in fact they can only confirm malnutrition).
This should be of particular concern to parents, since most parents, when they see their child starting to exercise or diet, then losing weight to the point of emaciation, do not even consider the possibility that an undiagnosed chronic illness may be preventing their child from establishing an appropriate appetite for their energy expenditure. In a normal, healthy individual, an increase in exercise is normally accompanied with an appropriate increase in appetite. In a person with an undiagnosed chronic illness, this is not always the case.
Although this site deals mainly with anorexia nervosa, it should be noted that there are also many chronic digestive disorders that can trigger binge eating and that may cause nausea and vomiting after eating. Habitual vomiting after meals may not indicate bulimia nervosa, but may instead be the result of a medical illness. Most recent literature on eating disorders use the term "bulimia", implying bulimia nervosa.
For clarity, throughout this site I will use the term "anorexia" to mean only appetite loss, without implying any mental illness. I will use the term "anorexia nervosa" to describe the phenomenon of extreme malnutrition combined with the perceived wilful avoidance of food and perceived fear of becoming fat. ("wilful avoidance" does not imply mental illness, since a person with a chronic digestive disorder "wilfully" avoids eating certain foods that cause gastrointestinal distress).I will use the adjective "anorexic" (or "anorectic") to describe a person experiencing loss of appetite, not implying any cause, either physiological or psychological. I will use the term "bulimia" to describe the phenomenon of vomiting after eating, not implying that this is strictly to avoid weight gain (some patients will vomit to avoid or reduce gastrointestinal distress and may actually feel better after purging). I will use the adjective "bulimic" to describe a person who habitually vomits after eating, not implying any cause, either physiological or psychological.