In "Siddhartha," how do the monks discipline themselves with regard to food and right thinking?

As Siddhartha seeks the enlightenment of losing his "self" he encounters the Samanas, and he seeks out and listens to the Buddha Gotama Buddha. He learns from each the concept of discipline of the self through meditation, and denial.  The monks discipline themselves through fasting, renouncement of all material things.  As Siddhartha says to Govinda,

"You have renounced home and parents, you have renounced origin and property, you have renounced your own will, you have renounced friendship.  That is what the teachings preach, that is the will of the Illustriouls One."