Fasting involves our separating ourselves from food for a season in order to draw close to God on behalf of others. This practice can be easily perverted into a religious activity to be seen of men (as Jesus reminded the Pharisees) or something that is performed while tolerating strife, debate, and self-interest (Isaiah 58:3-4).
Isaiah said that the fast God has chosen is one that focuses on the needs of others. When we become so burdened about a yoke of oppression upon the life of another that we refuse to partake of our normal food until that person is delivered, God is pleased (Isaiah 58:6). For example, Daniel fasted, not for himself, but for the nation to be returned from Babylon (Daniel 9:3).
If we spend ourselves on behalf of the hungry, then God will bless us with light, health, and water (Isaiah 58:8-11). Our light will be a guide through dark places, our health will give physical prosperity and strength, and our water will provide emotional and spiritual joy in times of drought. As someone once said, “Fasting is another way of feasting!”