I finally get it.

Why is anorectic different from the crash-dieter?
Different from the EDNOS girl who frequently restricts but has her binging days?
She's different because she can't eat. She doesn't want to, and her body physically won't let her anymore. She's been playing this weight game too long to back out now. She's addicted. It's not about being fat--it may have started out that way, but she'd not stupid. She knows how skinny she is.
No, emaciated. Skinny is too nice of a word.

She's playing a game with Death: a game in which she only loses and Death ultimately wins.
She sees how hopeless it is to fight her mind. Habits die hard. She doesn't won't can't eat. Her only joy is seeing the numbers on the scale fall. She knows she's killing herself by not eating; it's gonna happen sooner or later.

Might as well die doing what you love. Might as well make it sooner.

Now it's a hopeless race against time: the Race to Zero.
Size Zero? Oh no, that's much too big.
Zero Stone.
Zero Kilos.
Zero Pounds.
Zero Ounces.
Zero Grams.
Ultimate Zero.

...Nothing but Death will stop her from reaching her goal, and stop her it will. She needs to get as close as possible, though, so her life's work isn't a complete waste.
Not like she's already wasting away or anything.

It's too late for the anorectic.
She no longer has hope.
But not because it isn't available.

It's because she refuses it.