What significant event happens in the spring of Plum's junior year of high school in the novel, Dietland?

In the spring of her junior year, Plum stays home with an illness and sees a series of commercials advertising the Baptist Diet Plan. Plum becomes fascinated by the image of Eulayla Baptist bursting through a paper photograph of her former fat self and the interjection of the italicized word "Burst!" (38) quickly becomes a motif within the narrative.