My first guess was an eating disorder too....
She has many of the behaviors and symptoms....and the worst thing would be to be living under a roof with someone who notices your eating habits.
Bulimia would explain the somewhat odd "likes to eat" comment.
http://www.ajc.com/metro/content/metro/gwinnett/0505/08bride.html
The aunt asked Jennifer if it was OK to pass along Jennifer's phone number to the runner, a Duluth guy named John Mason. Sure, Jennifer said.
Mason called her. Not long afterward, the two went on their first date. Things clicked.
"He said, 'She likes football, she likes to eat and she's a Georgia Dogs fan,' '' said Melinda Larson, a member of Mason's running club. The relationship, Larson said, exuded "positive energy."
Well, she probably was going to have dinner after she ran ... so she went to Vegas on a bus to avoid the meal?
Maybe that's the "mental" part of it -- she wanted to disappear so she did, literally?