The Holy Communion Fast
Question: Why do I need to fast and how long must I fast before receiving Holy Communion?
Answer: We fast before receiving Holy Communion so that there is a desire for the heavenly food—the Bread of Angels. Fasting makes room in the body, soul, and mind for the Lord. Since we are body-soul beings, when the body is denied comfort and satisfaction of food and drink, the soul desires something divine to fill that void. The fast increases mental and spiritual alertness and fosters a hunger for the Eucharist.
As to how long we must fast, there are multiple layers to answering this question. According to Canon 919 §1, “A person who is to receive the Holy Eucharist is to abstain for at least one hour before holy communion from any food and drink, except for only water and medicine.” Note that it says, “before communion”; not “before Mass.” An hour before Mass is better, especially to increase our desire for the Lord in the Eucharist, but an hour prior to communion is all that is required. The two exceptions listed are water and medicine. That means all other substances break the fast. This would include things like tea, coffee, and chewing gum.
Canon 919 §3 gives another exception: “The elderly, the infirm, and those who care for them can receive the Most Holy Eucharist even if they have eaten something within the preceding hour.” This exception is given for those who are unable to fast without seriously endangering their health. It also recognizes that those who may be in the hospital, nursing home, or even homebound may not have known someone was coming to bring them Communion. For the good of body and soul, even if they have had food and drink within the previous hour, they are exempt from the fast and may receive.