Staying Fat For Sarah Byrne by Chris Cructher

Since grade school, obese Eric (Moby) has been best friends with Sarah Byrnes, a girl who was horribly disfigured by an accident at the age of three. In high-school Eric joined the swim team and began to slim down. Fearing that Sarah would feel alienated by his new appearance he tried to "stay fat" for her for almost a year, until Sarah pointed out to him that their lives were bound to eventually go in different directions but that their friendship would not be affected by his weight loss. But now Sarah is in a near-catatonic state in the pychiatric ward of the hospital and Eric is desperate to help her. As he hopes for a break-through with Sarah, he and his friends question why this is happening to her and what they can do - and there are no easy answers.

While the hardcover book jacket is a little dated, the characters and situations are as fresh and relevant as when the book was published in 1993.