The spiritual reasons for fasting have been pretty much lost on today’s society, particularly in Protestantism. Many United Methodists are surprised to learn that John Wesley fasted two days a week, Wednesdays and Fridays, in his younger days. Later he fasted on Fridays. Charles Yrigoyen, Jr., in John Wesley: Holiness of Heart and Life writes:
Wesley was convinced that fasting, abstaining from food or drink, was a practice firmly grounded in the Bible. People in Old Testament times fasted (Ezra 8:23). So did Jesus and his followers (Matthew 4:2; Acts 13:3), and Wesley saw no reason why modern Christians should not follow the same pattern. His plan of fasting sometimes allowed for limited eating and drinking. He found that fasting advanced holiness.
John Wesley: Holiness of Heart and Life copyright © 1996 Charles Yrigoyen, Jr., p. 33.