How does the author use foreshadowing in The Best Little Girl in the World?

There is a short poem at the beginning of the book that reads, "Fat and Skinny had a race; All around the pillow case. Fat fell down and broke her face. Skinny said, "Ha-ha, I won the race". This personification of "Fat" and "Skinny" are a foreshadowing of the battle Francesca will fight within herself and that seems to be at the heart of the illness itself.