It's a difficult but valuable experience for a person at any age. If you live a fairly healthy and normal life it may be difficult and even frightening to hear what her internal experience is. Often people with an eating disorder firmly believe that they are on a destructive path and that their behavior will kill them. Yet, they cannot stop. They know they are killing themselves.
Some people are certain that no matter what day it is, they have six months to live from that day.
They cannot plan a future or take anything or anyone really seriously since they don't believe they will be alive long enough to follow through on anything. When you discover that someone you know is bulimic or anorexic, you may question your criteria for evaluating the world and the people in it. Most of the time you can't easily identify someone who has an eating disorder. Some people are skeletal. Some are normally weighted.