A summary:-

1.  Jesus is recorded just once as having fasted.  This was at the time of his temptations in the wilderness.  It is not clear how deliberate this fasting was.  On the one hand, the first temptation implied that there was no food available in that place, Mt 4:1-4.  On the other hand, we should probably assume that Jesus went to that place knowing that there would be no food.

2.  Jesus assumed, rather than commanded, that his hearers would fast.  He taught that they should do so with a Godward, rather than a manward, attitude, Mt 6:16-18.  He was once asked why his disciples did not fast as often as those of John the Baptist: he did not repudiate fasting, but replied that it would be inappropriate for them to fast while he was still with them, Mt. 9:14–17; Mk. 2:18–22; Lk. 5:33–39).

3.  In Acts important decisions were preceded by fasting, Acts 13:2–3; 14:23. Paul refers twice to his fasting, 2 Cor. 6:5; 11:27. The former passage seems to refer to voluntary fasting, as a way of self-discipline.  The latter passage mentions both involuntary ‘hunger’ and voluntary going ‘without food’.

4.  There several disputed texts that refer to fasting (Mt. 17:21; Mk. 9:29; Acts 10:30; 1 Cor. 7:5).  The presence of these in some manuscripts testifies to a growing interest in fasting in the early church.

See New Bible Dictionary, art. ‘Fasting’