The time [of "One Fat Summer"] is 1952, and Lipsyte mingles the flavor of the era in his prose; the issues, tastes and expressions of the day echo through the narrative….
[The] first-person narrative gives us an inner perspective of Bobby's thoughts and feelings. Refreshingly, he is neither precocious nor off-beat, in the manner of so many teen-age protagonists, but simply a normal boy in abnormal circumstances.
Bobby, however, is Lipsyte's only fully realized character; the supporting cast shifts in and out of the reader's focus, not only because of the plot, but also because our perception of them varies. For example, Bobby's father is alternately stiff, compassionate, machine-like and impulsive. His mother is sharp, sensitive, but sometimes blindly overprotective. In one way, these contrasting qualities reflect the changing ways in which Bobby sees them. In another way, they're confusing.
Nonetheless, the dramatic movement of Bobby's metamorphosis is effectively rendered. As the summer progresses, he sheds pounds and illusions in equal measure, and in the process, both his mind and body begin to shape up. His long struggle culminates in the realization that he has the independence to meet life on his terms—and that's a weighty enough idea for anyone.
Stephen Krensky, "Children's Books: 'One Fat Summer'," in The New York Times Book Review (© 1977 by The New York Times Company; reprinted by permission), July 10, 1977, p. 20.