The days will come when the bridegroom is taken away from them, and then they will fast. (Matthew 9: 15)
Then the disciples of John came to him, saying, “Why do we and the Pharisees fast, but your disciples do not fast?” And Jesus said to them, “Can the wedding guests mourn as long as the bridegroom is with them? The days will come when the bridegroom is taken away from them, and then they will fast. (Matthew 9: 14-15)
The fasting which John the Baptist's followers speak about is abstinence from physical food. The fasting which Jesus refers to, on the other hand, is the absence of His presence, the presence that gives true and eternal life. This abstinence from Jesus' presence happens on Good Friday and Holy Saturday, two days when the Mass is not celebrated. Are we aware of the importance of Christ's Real Presence in the Eucharist?