Anorexia nervosa is a psychiatric illness that primarily effects young people during their adolescence. While anorexia is relatively uncommon, affecting about 1 percent of the population, it can be lethal. Indeed, despite its relatively early onset, anorexia can last for several decades for more than half of those afflicted. It can lead to many associated psychiatric and medical risk factors, which in part explains why anorexia has the highest mortality rates of any psychiatric disorder.