Anorexia is literally 'nervous lack of appetite'. The scientific name is 'Anorexia Nervosa'. The main characteristics are:

  • The deliberate and prolonged restriction of calorie intake, leading to considerable weight loss. 'Considerable' in this case means falling to more than 15% below normal weight.
  • Most commonly, it affects middle-class, adolescent girls, although cases involving males have increased recently.
  • Anorexics often have a 'disturbed' body image. That is, they see themselves as fat, even when they are thin.
  • Anorexia regularly leads to loss of menstrual cycle ('amenorrhoea')
  • Anorexics often fear gaining weight, although they can be very hungry and preoccupied with food, and cooking for others etc.

So, what is there that explains Anorexia? Unfortunately, we can't open up the brain and see how it works; we can only hypothesise, and look at what little empirical evidence we have.

Genetic Transmission
In 1984, a guy called Holland wanted to find out if anorexia was genetically transmitted. To do this, he got a group of people who were twins, where at least one twin was anorexic. You can get identical and non-identical twins. Both types are born at the same time to the same parents, and thus they have most environmental influences the same. But identical twins have exactly the same genetic material, whilst non-identical twins have different genetic material.

From the identical twins, if one twin had anorexia, there was a 55% chance that the other twin also had anorexia. If they were non-identical, there was only a 7% chance that both twins would have it.

This study suggests that anorexia is partially transmitted genetically. But environmental factors also play a part, otherwise there would have been 100% concordance between identical twins.

Biochemical abnormalities
Disordered hormones may be a cause. Loss of periods may occur before weight loss, indicating an endocrine system disorder. In 1989, a guy called Fava found changes in levels of noradrenaline and seretonin in anorexics. This explanation is strong in that it can explain why anorexia is linked to adolescence (because adolescence is a time of hormonal change). The problem is it's hard to separate cause and effect; do chemical changes cause anorexia, or does anorexia cause chemical changes?

Autonomy
Anorexics tend to have somewhat obsessive personalities, with low self-esteem and a fear of their own anatomy. A guy called Brunch suggested in 1987 that certain mothers encourage anorexia by encouraging their daughters (and sons) to be dependent, leading them to assert autonomy by exercising control over their own bodies. The fact that anorexics often come from middle-class families where there are high expectations would seem to support this. Autonomy could also explain why anorexia is common in teenagers.

Conditioning
Knowing that eating too much makes people overweight, Anorexics could be classically conditioned to feel anxious about eating.

Weight loss is self-reinforcing, because people praise it. The person has escaped a negative Stimulus.

Feminine stereotypes in the media promote the desire to be thin. Vulnerable individuals emphasise this. This explains why Anorexia is more common in western cultures than in, say, Japan.

In conclusion, there is no definitive answer as to what causes anorexia, but it is likely partially genetic. It is also at least partially down to environment, and upbringing. There is no 'easy answer'; it is, like so many things, a combination of factors. But with time and help from others, most sufferers recover, and few things matter more than that.

Most people use anorexia to mean "anorexia nervosa". Technically, though, when the term is used by itself, it simply refers to a reduced desire for food; it doesn't actually imply anything about the causes of that reduction. Anorexia in this sense is a common symptom of several conditions, including gastrointestinal disorders, neurological disorders, and cancer; it's also a side-effect of a wide variety of drugs, some of which are actually designed to produce a decrease in appetite. (I've known a few people who freaked out when they saw "anorexia" listed as a side-effect of a drug--they thought that they were going to end up with low self-esteem, an insatiable desire to exercise, and a distorted body image; in reality, they were going to experience at most a minor reduction in appetite.)

An`o*rex"i*a (#), An"o*rex`y (#) n. [Gr. ; priv. + desire, appetite, desire.] Med.

Want of appetite, without a loathing of food.

Coxe.

 

© Webster 1913.

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