Answers
What is fasting and should I do it?
Fasting is going without food for a set time in order to put weight behind prayer, and Jesus said when you fast, not if. It is not a hunger strike aimed at God and it does not purchase anything. Start small — one meal, one day — keep it secret, drink water, and spend the time you would have spent eating in prayer instead. Do not fast from food if you are pregnant, diabetic, unwell, underweight, or have any history of trouble with eating; fast from something else, and take medical advice first.
Go and see for yourself
Moreover when ye fast, be not, as the hypocrites, of a sad countenance: for they disfigure their faces, that they may appear unto men to fast. Verily I say unto you, They have their reward.
Matthew 6:16
Is not this the fast that I have chosen? to loose the bands of wickedness, to undo the heavy burdens, and to let the oppressed go free, and that ye break every yoke?
Isaiah 58:6
So we fasted and besought our God for this: and he was intreated of us.
Ezra 8:23