One of the great tragedies of anorexia is that a skeletal body means so much more than thinness. The body's organs are breaking down. The hormonal system has lost a healthy balance. Cells of the brain are starving.
All this contributes, not only to severely damaged health, but also to impaired thinking. A malnourished brain does not function well.
The person in such a state suffers from distorted perceptions and unrealistic thinking. If this were Brittany's situation then she would be vulnerable in many, perhaps all, areas of her life.
When a person's ability to make reasonable evaluations about her life choices is weakened or crushed entirely, she can be adamant in following a destructive, even lethal course.
Anorexia sets up a person to die by destroying the body and creating a mindset that supports dangerous choices.
So sad. She was dear in "Clueless."
I hope your death helps people who are denying themselves nourishment to eat and regain a realistic perspective that supports their lives.