Bale gained attention for his devotion to the role and for the lengths to which he went to achieve Reznik's emaciated, skeletal appearance. He went without proper rest for prolonged periods, and placed himself on a crash diet of generally coffee and apples,[27] which reduced his weight by 63 pounds (4 st 4 lb/27 kg) in a matter of months.[28] By the end of filming Bale weighed only 121 pounds (8 st 9 lb/55 kg)
Still fresh off The Machinist, it became necessary for Bale to bulk up to match Batman's muscular physique. He was given a deadline of six months to do this. Bale recalled it as far from a simple accomplishment: “...when it actually came to building muscle, I was useless. I couldn’t do one push up the first day. All of the muscles were gone, so I had a real tough time rebuilding all of that.”[28] With the help of a personal trainer, Bale succeeded in meeting the deadline, gaining a total of 100 lb (45 kg) in six months. He went from about 130 lbs to 230 lbs.[35] He then discovered that he had actually gained more weight than the director desired, and dropped his weight to 190 lbs by the time filming began.[36]