blogged about three purposes of fasting. Using Moses, Elijah and Christ as examples, I wrote that we could fast for our own welfare, the welfare of others or to bring our souls in communion with God.
These examples remain powerful. Consider the Sons of Mosiah who fasted before their missions to the Lamanites (Alma 17:2-3) or the disciples of Christ who fasted to add power to priesthood blessings (Alma 13:1-3, Matthew 17:14-21). Each of these are further examples of the power of fasting for yourself or others and each has obvious outward consequences-- a converted Lamanite people, healings, etc.
Fasting to bring our souls in communion with God is also extremely private (Matthew 6:16-18, 1 Cor. 7:5). Through fasting we can follow Isaiah's charge to seek strength against temptation (Isaiah 58:3-12). We can express our deepest sorrow, as Elijah did for his sinful people (1 Kings 19:8-18) or as the people of the Book of Mormon mourned the loss of those who had died (Alma 28:6, 30:1-2, Helaman 9:10). We can also express to God our gratitude and great joy for the blessings He has given us (Alma 45:1, D&C 59:13-14, Luke 2:36-37).
A sincere and willing fast allows for self-expression beyond words. God knows and understands even our most inexpressible feelings; we give volume to those feelings through fasting. Simultaneously, fasting makes each of us better listeners, so that in giving our will to God we receive not only a better outlet to express our souls but also a better method for learning spiritual truths.
In fasting we can become like the Nephites just prior to the coming of Christ:
Nevertheless, they did fast and pray oft, and did wax stronger and stronger in their humility, and firmer and firmer in the faith of Christ, unto the filling their souls with joy and consolation, yea, even to the purifying and the sanctification of their hearts, which sanctification cometh because of their yielding their hearts unto God. ~Helaman 3:35
Fasting can be intensely personal, powerful and uplifting. It can express or strengthen or change even the deepest portions of our souls or the souls of those for whom we fast. As we fast often and with sincerity, we can become sanctified and pure-- better people, better spouses, better friends, better parents, better disciples of Christ.
That is the kind of Is this the fast you have chosen?