Albert Barnes Commentary Mark 2:18

"And John`s disciples and the Pharisees were fasting: and they come and say unto him, Why do John`s disciples and the disciples of the Pharisees fast, but thy disciples fast not?" — Mark 2:18 (ASV)

And the disciples of John and of the Pharisees used to fast. Were accustomed often to fast. Compare Luke 5:33; Luke 18:12.