The phrase "feed upon" can be expressed in many ways, depending on the context and the message being conveyed. Some possible synonyms for "feed upon" are "nourish," "consume," "feast on," "devour," and "ingest." "Nourish" refers more to the process of providing sustenance, while "consume" and "ingest" have a more neutral connotation. "Feast on" and "devour," on the other hand, connote a more intense, voracious kind of feeding. Other possible synonyms for "feed upon" include "eat," "chew," "swallow," "gorge," and "sate." Choosing the best synonym for "feed upon" depends largely on the tone, intensity, and purpose of the communication.