Disordered eating often (but not always) occurs in affluent cultures, especially in America, where anorexia nervosa (voluntary starvation) and bulimia nervosa (binge-eating followed by purging) now afflict one in ten people.
Most of the diagnosed are young women in their teens and 20s, but the prevalence is increasing among young men each year.
Among the most baffling of conditions, eating disorders take on a life of their own so that eating, or not eating, becomes the point of everyday existence. Both anorexia and bulimia are powered by a desire for control.
But in another eating disorder, binge-eating, in which people gorge on large amounts of food and generally gain weight, sufferers feel that eating is out of their control.
Both culturally mediated body-image concerns and personality traits like perfectionism and obsessiveness play a large role in creating eating disorders, which are also often accompanied by depression and/or anxiety.
There is no magic cure for these conditions, which are often resistant to treatment, and many cases can be acutely life-threatening, requiring hospitalization and forced nourishment.