Agree with everything posted above about Sarah. She's in such deep denial that what she's doing is detrimental, and she's deeply selfish for not caring about the horrible effect she could have on others. That's what really upsets me. Most people I've met with restrictive EDs are unnecessarily self-critical and blame themselves for everything. She has such a horrible personality that she's the exact opposite, in the sense that she has this disgusting pride in what she does and that's just reinforced by her speed/progression at running.
The only way she'll ever change is if she finally gets what's coming to her in terms of injuries. Without a series of stress fractures, or even full fractures, she can continue to live a lie, suck up to her coaches so they stick their fingers in their ears and sing lalalala I can't hear you when people point out the fact they shouldn't be reinforcing her behaviours and enable her, and brag about how emaciated she is at every possible opportunity.