Fasting is symbolic of sharing in the death of Christ. Its connotation is abstention from food because food is the sustenance of life and its absence is a token of death.
The road to holiness articulates that we should also fast from worldly things so that we may die to the world and gain Christ,
Isaiah 58:1-10 tells us that we should not fast so that people will feel sorry for us and think we are pious. We should not worship “worship”. Just because we pray and fast, we think we are better than other people. It also tells us to stop corruption and to stop taking advantage of people, especially the poor. At the same time fasting should be the occasion for forgiveness, for sharing our blessings with the needy, and for promoting and advocating justice for everyone.
“One does not live by bread alone, but by every word that comes forth from the mouth of God.” (Mt 4:4) Thus, true fasting is not only abstaining from food and worldly things but also by being humble, and by following what Isaiah 58:1-10 tells us. (It is worth noting that the Catholic Church in the United States requires only 2 days of fasting – Ash Wednesday and Good Friday. The obligatory fasting is for persons who are 18 to 59 years old. When fasting, only one full meal and 2 small meals are allowed.)