EWTN Catholic Q&A
Fasting after Communion?
Question from Anonymous on 12-23-2016:

I know that it is part of canon law that we must fast for 1 hour before receiving Holy Communion. I have also heard of the idea of not eating anything for 15 minutes AFTER receiving Holy Communion.

Is this second item also part of canon law, or is an optional devotional practice?

Thank you.

Answer by Colin B. Donovan, STL on 03-14-2017:

It is not explicitly a matter of the law, it follows from the Church's teaching about the Eucharist. We fast before receiving so as not to receive Jesus while still full of ordinary food. After we have consumed the Host, the Church's teaching is that Christ is Present as long as the "accidents," or characteristics, of bread and/or wine remain. This is likely at least 10 minutes to as long as 15. We show our respect for Him by making a Thanksgiving and not eating for that time. By the time Communion finishes and the Mass is ended probably most of that time has passed, so it is not really much of a burden to wait a few minutes more.

Sine the Church understands human nature she makes allowances for those who are sick or frail. Before Communion the law is reduced to 15 minutes, and even 0 if necessary. Likewise, afterwards. If you can't wait 10-15 minutes after Communion for a just reason, such as having low blood sugar, you may.