Christ didn't teach that we must fast every Friday and Wednesday, so it must not be what Christ wants.
Yes he did. See Apostolic Canon 69:
"If any Bishop, or Presbyter, or Deacon, or Subdeacon, or Anagnost, or Psalt fails to fast throughout the forty days of Holy Lent, or on Wednesday, or on Friday, let him be deposed from office. Unless he has been prevented from doing so by reason of bodily illness. If, on the other hand, a layman fail to do so, let him be excommunicated."
Who do you think instructed the Apostles?