The primary purpose of fasting is to gain the benefits provided through spending extra time praying and seeking the Lord. There is hardly a reference to fasting in the Bible that does not also contain a reference to prayer, leading us to believe that it is pointless to fast without praying. Both references to fasting in the book of Acts, for example, mention praying. In the first case (see Acts 13:1-3), the prophets and teachers in Antioch were simply “ministering to the Lord and fasting.” As they did, they received prophetic revelation, and consequently sent Paul and Barnabas on their first missionary journey. In the second case, Paul and Barnabas were appointing elders over new churches in Galatia. We read,
When they had appointed elders for them in every church, having prayed with fasting, they commended them to the Lord in whom they had believed (Acts 14:23).
Perhaps in this second case, Paul and Barnabas were following Jesus’ example, as He prayed all night long before choosing the twelve (see Luke 6:12). Important decisions, such as appointing spiritual leaders, need to be prayed about until one is certain he has the leading of the Lord, and fasting could give more time for prayer to that end. If the New Testament commends temporary abstinence from sexual relations between marriage partners in order to increase devotion to prayer (see 1 Cor. 7:5), then we could easily understand how temporary abstinence from eating could serve the same purpose.
Thus when we need to pray for God’s direction for important spiritual decisions, fasting lends itself to that end. Prayers for many other needs can be made in a relatively short time. We don’t need to fast, for example, in order to pray the Lord’s Prayer. Prayers for guidance take longer because of our difficulty in “discerning God’s voice in our hearts,” as God’s voice often competes with any wrong desires or motivations, or lack of devotion that may be within us. Gaining assurance in guidance can require an extended period of prayer, and that is one instance where fasting is beneficial.
Of course, just spending any time in prayer for any good purpose could hardly be considered anything but spiritually beneficial. For that reason, we should consider fasting to be a wonderful means towards spiritual strength and effectiveness—as long as our fasting is coupled with prayer. We read in the book of Acts that the early apostles were devoted “to prayer and to the ministry of the word” (Acts 6:4). Surely that reveals to us at least part of the secret for their spiritual power and effectiveness.
 I have fasted for as many as seven days without any spiritual benefit whatsoever, for the simple reason that I had no spiritual purpose and did not spend any extra time in prayer.
 The King James Version of 1 Corinthians 7:5 commends the mutual consent of husbands and wives to abstain from sexual relations in order that they might devote themselves to “fasting and prayer.” Most modern English translations of this verse do not mention fasting, but only mention prayer.