Q:

What methods were used to make Christian Bale look so much like Dick Cheney in the film "Vice"?

Its pretty well known the lengths that Christian Bale has gone to in the past to play certain roles including both losing and gaining weight. The primary example I can think of being The Machinist (2004) in which he ate a diet of a can of tuna and an apple per day in order to lose 63 pounds.
Having just seen the trailer for the upcoming movie Vice (2018) in which he is set to play Dick Cheney, I have to say that I'm kind of amazed at the transformation of the actor to look like Dick Cheney. I in fact could not tell who it was until the trailer displayed Christian Bale's name on screen.
The other thing that came to my mind was the amazing transformation of Gary Oldman into Churchill for Darkest Hour (2017) which was largely due to prosthetics as well as, of course, phenomenal acting.
So, I'm left to wonder how much of Bale's transformation into Dick Cheney is due to prosthetics and makeup and how much is due to him going through a similar physical transformation as he's done for previous roles?

A:

Yes, he gained weight, did specific exercises, shaved his head, and used make-up artists.

To shape-shift accordingly, Bale has said that he shaved his
  head, bleached his eyebrows, and gained 40 pounds. (Co-star Carell
  also said that Bale did specific exercises to thicken his neck.) This
  January, Bale waved off any praise for the extreme
  character-preparation, telling Yahoo that he was just trying to
  provide “a blank canvas through which these incredible [hair and
  makeup] artists could create the various ages of Cheney. . . . They
  would shave my head every day, bleach and pluck eyebrows.”

