What is fasting and who and why must we fast?
Let’s take a look at the history in the Old Testament of fasting. The Hebrew word used in the Old Testament for fasting is the word “sum” a verb meaning to abstain from food. It is most often used with the Hebrew word “Ana” which means to deal harshly with oneself or self affliction. The word to fast is used 17 times in the Old Testament. This word fast in the Old Testament is always associated with abstaining from all food and drink. It appears from scripture that fasting always means not eating and not drinking. The meaning of the word itself is to abstain from food and drink. The practice in the Old Testament always seemed to mean abstaining from all food and all drink.
Deuteronomy 9:18 (ESVST)
Then I lay prostrate before the Lord as before, forty days and forty nights. I neither ate bread nor drank water, because of all the sin that you had committed, in doing what was evil in the sight of the Lord to provoke him to anger.
Fasting in the Old Testament was done when someone was morning 1 Sam 31:13, if there were public calamities 2 Sam 1:12, private afflictions or troubles 2 Sam 12:16, religious observerance Zac 8:19, when there is sickness 2 Sam 12:16, when one is about to approach danger Est 4:16, own troubles or affliction Ps 35:13 and it is clear that Israel fasted regularly Zec 8:19. Fasting was also in some cases commanded by God Joel 1:14.
This fasting seems to have been always accompanied by self denial Dt 9:18, confession of sins 1 Sam 7:6, reading scripture Jer 36:6 and/or prayer Dan 9:3. God does not accept fasting from those that are disobedient.
In the New Testament, there is a lot of evidence that fasting continued. The Greek word used for fasting is the word “nesteuo” a verb which also means to abstain from food. It comes from the noun “nestis” which means not eating. The word is used 16 times in the New Testament. 6 times in Matthew, 3 in Mark, 4 in Luke and 3 in Acts. In fact, Jesus also fasted for 40 days and nights in the desert after his baptism and others by John’s disciples (Mt 9:14); by Pharisees (Mt 9:14; Mk 2:18; Lk 18:12); by Anna (Lk 2:37); by Cornelius (Ac 10:30); by Paul (2Co 6:5; 11:27). So, this seems to be a practice that continued even in the church. Jesus has never critisised or spoke against fasting. However, Jesus spoke against hypocritical fasting. Jesus was saying in Matthews 6: 16-18, that if when you fast, you let the whole world know that you have fasted, then you already recieved your glory but when you fast, let no one know and your father who knows in secret and sees in secret, will reward you. Jesus also said that when he was with his disciples that they did not need to fast but they will fast when he has gone back to heaven in Mark 2:18-22. So, fasting seems to have continued throughout the early church.