For a very long time, anorexia was thought to be a widespread mental health problem among adolescents, and caused by environmental factors such as problematic, control obsessed parents, low self-esteem, societal role models, or a general fear of growing up. Some of this is still believed to be true today, and some of these factors may have a bearing on the onset of the disease, but there is so much more to it: first and foremost, it has been discovered that anorexia has biological and genetic origins.
The overall results of a vast number of studies show that between 60% and 85% of the risk that a person may develop anorexia lies in their genetic makeup. However, there is no single "anorexia gene": anorexia, as with all other eating disorders, is a very complex disease, in which various different genes contribute to the onset of a person’s susceptibility to it. In the majority of cases, anorexia develops during the very first years of adolescence, and this could be linked to the onset of puberty. In fact, it is precisely at the time of puberty that any genetic predisposition to the disease begins to activate.
Certain environmental conditions are immediately linked to this genetic predisposition. In fact, during adolescence, young people experience many changes: the complexity of the social and emotional issues that adolescents have to deal with increases, as does the pressure and influence from their peers. It is at this stage of our lives that we also begin to participate in mainstream culture, and are therefore exposed to the concept of stereotypical appearances or physical health issues for the first time. These types of exposure will make up the remaining 15% to 40% risk of developing anorexia for those who already have the genetic predisposition mentioned earlier.
In other words, anorexia is mainly a biological disease, and one whose roots can be found in our genes, but socio-cultural factors certainly do have their role to play. They are able to influence which genes are expressed more intensely than others in our DNA, thus functioning as a "switch" for the genes that make us predisposed to anorexia. Sometimes it takes very little indeed to trigger the illness: in the book the author describes a girl who developed anorexia after a friend simply said to her "you're lucky you're so thin", a comment that quickly led her to becoming obsessed with counting calories to hold on tightly to that "luck".
With a disease like anorexia, it is almost impossible to distinguish its natural and biological causes from those dictated by culture, society and environment. The sociocultural and psychological components exist primarily in the typical language of Western culture that many anorexic people use to justify their behaviour, such as "keep fit", "eat better", "lose a few pounds". But this language only goes to mask a behaviour that is actually driven by an irrational fear of food and getting fat.
So the socio-cultural component does have its role to play, but the issue is very layered. If environment were the only factor, it would not explain how many cases of anorexia emerge even in countries whose culture is very different from that of the West, and even among the Amish who, notoriously, do not have access to television and fashion magazines. Rather, what anorexia relies on is the ability to provide relief from anxiety, the ability to channel anxiety and depression into something specific like absolute control over calorie intake.
The fact that anorexia is a biologically based mental illness does not mean that psychological help is ineffective, that the environment does not influence it, or that there is nothing the patient can do to prevent or recover from it. Quite the opposite, knowing that anorexia has a strong biological component helps people who suffer from it to free themselves from strong feelings of guilt, which enables them to change their attitude towards the disease.