Something such as powerful and deadly as bulimia is not based around mere society, however. In the family of someone vulnerable, there is usually chaos. Emotions are erratic and scattered and the person isn't taught how to deal with things very well. It is often described that the mother has been the type to diet constantly herself, and moreso than anorexia there tends to be a past history of sexual abuse. Somewhere the feelings of unworthyness and failure build and erode the person's self-esteem, whether that be the person feeling inadequat in their parents' eyes or perhaps even a boyfriend's eyes.
Food brings comfort and purging the relief into the person's body and mind.
Purging also causes a sick sense of control, as well. Knowing that they can basically eat what they want and just bring it all up later helps the person feel better and in control of what they allow their bodies to have and digest. As with anorexia, the person with bulima will measure everything by one object - their bodies. Their body and their weight will commonly measure whether the day will be good or bad, and whether they are allowed to eat. Becuase bulimia does not cause someone to lose an extraordinary amount of weight, it is generally an easy disorder to hide.