She is very thin and tired, and is developing a wispy-type of body hair all over her body, because her body is keeping her body warm. Her hair is falling out, because the body is using its nutrients for her organs instead of her hair and nails.
2) What emotional/mental/behavioral signs of an eating disorder is Mariana developing?
She is very hard-working and tries hard to please others, which means that she probably thinks her weight isn't good enough. She's a perfectionist and likes to be in control.
3) What eating disorder do you think she has?
4) What other signs of the eating disorder (not mentioned in the story) could you look out for?
Cutting up or playing with her food when she eats around other people. She could be constantly talking about weight-loss, or obsessing about certain features of her body and insisting that they're fat.
5) Where can Claudia go to help her friend?
She could speak to an adult, like a health teacher or a counselor, and also try talking to her friend. She could tell her that she needs help and that what she's doing is not healthy. She could also tell Mariana's parents that she's worried and that they need to have a talk with Mariana.