Lia Overbrook and Cassie Parrish have been best friends since the third grade, but as they grow up, both develop destructive obsessions with body image, dragging each other down because each is afraid of dealing with her demons alone. Lia is anorexic, while Cassie is a victim of bulimia, and when the going gets too tough in the months before their senior year in high school, Cassie breaks off the friendship, leaving Lia devastated. Six months later, after not having communicated with her ex-friend in ages, Lia receives thirty-three phone calls from Cassie in one evening, but she refuses to answer. When she discovers the next day that Cassie has died a grisly death brought on by her own excesses alone in an isolated motel room, Lia realizes that Cassie had been calling for help, and she is wracked by guilt. Lia's parents, divorced and absorbed in their own careers, are unaware of the severity of their daughter's torment, and Lia keeps them, along with her father's new wife, at a distance, adeptly concealing her inner turmoil and maintaining an appearance of normalcy. Lia's fragile hold on health and reality is tenuous at best; haunted by Cassie's ghost, she finds herself losing control of her life, sinking into an abyss of cutting and self-imposed starvation that can only end in her own destruction.

Laurie Halse Anderson's 2009 novel is a devastating account of a young girl's descent into self-abuse and despair, a state where

You're not dead, but you're not alive either. You're a wintergirl caught in between two worlds. You're a ghost with a beating heart.

Having subconsciously created "a metaphorical universe" of visions and obsessions to assuage the pain of her own isolation, Lia hates the pattern of her own behavior but is powerless to stop it. Her perceptions are hopelessly distorted, and she starves herself to rid her body of repulsive bulk visible to her eyes alone. It is only when her life is in critical danger that she finally comes to the realization that no amount of weight-loss will ever be enough for her, and she is able to acknowledge the seriousness of her condition and seek help to get better. Lia's story ends on a hopeful note, but it is clear that the struggle for wellness will be grueling, and comes with no promises. In Wintergirls, the author handles a difficult problem with unflinching realism and honesty, making this offering a valuable addition to the canon of young adult literature.