With Henry Cavill set to reprise his role as Superman after his successful first outing in "Man of Steel," the world of entertainment now awaits who Warner Bros. and Director Zack Snyder will select to slip on the bat cowl and become Gotham's dark knight. The two heavyweights of the comic book world are set to go up against each other in "Superman vs. Batman," slated for release in 2015. While we know absolutely nothing about the plot line (with the exception of some inspiration from Frank Miller’s "The Dark Knight Returns"), it's clear that both lead actors are going to need every moment in the gym to transform themselves and get into superhero shape. 

Below are the diets and routines that were used by Christian Bale as Batman in the Christopher Nolan trilogy and Henry Cavill as Superman in "Man of Steel." With production on "Superman vs Batman" set to being in 2014, you can bet that producers are already eager to get their leads in they gym. Here's how they'll likely bulk up for the comic book world's most anticipated big screen battle. 

Christian Bale as Batman

The Batman diet

Though rumors have surfaced indicating that Zack Snyder may be looking for an older actor to play Bruce Wayne, the physical demands present in Nolan’s trilogy will likely still be the same.

The most valuable insight for anyone looking to mimic the physicality of Christian Bale’s Batman comes courtesy of the transformation he underwent for “Batman Begins.” Prior to agreeing to star in the role, he was just finishing up work on the 2003 film “The Machinist,” for which he dropped 63 pounds from his normal weight of 185 pounds. He then had only six months to transition his body for the Batman movie. 

“I had to put on a great deal of weight, which was necessary for the character. He has no superpowers, so you have to believe he's capable of this,” Bale told the BBC. “I kind of knew I could do it. I think Chris [Nolan] was probably worrying far more than me. I was talking to him one time on the telephone whilst we were doing 'The Machinist' and he'd say, ‘How're you looking these days?’ "

“It was frankly pathetic, I was down to 121 pounds and I couldn't do a single push up — this is maybe not the guy you want to cast as Batman. But we had enough time. It was an arduous journey to get there, but I managed to get into appropriate shape by the time we started filming.”

Bale reportedly packed on 60 pounds for his Batman screen test through a high-carb diet of bread and pasta. He then added an additional 39 pounds over the next three months by eating chicken, tuna and steamed vegetables.

For anyone looking to achieve similar results, you may want to space out the weight gain. According to Bale, it didn’t make him the happiest person in the world. 

"You do get a lot of nervous energy,” he told IGN. “I think putting weight on, unfortunately I had to put it on pretty fast and it's not very healthy doing that. That was when I felt bad. I did actually start to feel I was putting my body under too much pressure because I put on 100 pounds in five months. You get big mood swings, but not such a bad thing when you're playing this darker version of Batman.”

Christian Bale as Batman

The Batman workout

Once again referencing Bale’s routine, the actors says he underwent daily three-hour running and weight-training sessions. For a Hollywood actor with a personal trainer, this is easy to accomplish. For the rest of us not preparing for a screen test, an hour in the gym several times per week will likely give you similar results. Below are some Batman-inspired workouts from various sites that will help you achieve a similar look over a more comfortable amount of time. 

The Superman diet

Henry Cavill as Superman

While Batman's armor provides him with an intimidating look all its own, Superman's skin-tight outfit is fully dependent on the actor having a ripped body to pull off the superhero look. For "Man of Steel" star Henry Cavill, already in good shape from his 2011 film "Immortals," that meant bulking up with an additional 20 pounds of muscle. 

Unlike Bale, Cavill had 11 months to essentially eat as much as possible, workout constantly, and then tighten his diet to burn off fat and create a more toned physique. 

"The best thing about that [first] phase is that you’re really strong and even though you don’t look great, because you’re carrying a lot of extra fat, you’re always in a really good mood," he told Glamour UK. "The leaning down phase is the hardest, because although you’re looking great, you’re always in a bad mood because you’re so hungry.” 

Unlike restrictive bulking up diets like the ones Bale, Hugh Jackman, or Benedict Cumberbatch adhered to, Cavill's trainer Mark Twight let the actor eat whatever he wanted to fulfill a requirement of 5,000 calories per day. 

"We didn't care," Twight told "Good Morning America's" Abbie Boudreau. "If he decided, I can get an extra 1,000 calories by eating pizza, that was fine."

That being said, Cavill did have some diet guidelines. "You’ve got to eat protein first, then a little bit of carbs … you’ve gotta keep your hunger levels going," he told Total Film. "I’m training two and a half hours a day, pushing my body beyond its normal limits, putting on a lot of muscle mass and just making myself look like Superman.”

Cavill as Superman

The Superman workout

When Cavill finished his last shirtless scenes for "Man of Steel," he happily indulged in some less-than-super junk food. 

"Zack Snyder bought me an amazing apple pie and a tub of ice cream," he said. "Then I ordered a pizza as well, and didn’t even go home — I just sat in a trailer afterwards and ate it. I passed into a food coma after that."

Unfortunately for the 30-year-old, with Warner Bros. fast-tracking the sequel, he's going to be hitting the weights consistently to return to form — a process that reportedly involves 2.5 hour workouts six days per week. It's also worth noting that Cavill and Twight took no shortcuts in getting there. 

"He asked me a lot of questions about my goals," Cavill said about his initial interview with his trainer. "Then he asked, ‘Would you like to do steroids or HGH to get you where you want to go?’ ‘I immediately said no.’ And he said, ‘Good, because if you did, I wouldn’t train you.’"

Below are some workouts from various sites inspired by Cavill's routine for "Man of Steel." You can also view a National Guard video of the actor working out for the role below. 

Conclusion

However Batman and Superman end up going at each other, it's clear that each superhero is going to have to be at the top of his game physically to believably match up. It's a process that definitely won't be easy, but in an age of endless CGI enhancements, it's somewhat satisfying knowing that actors looking to play iconic comic book characters still have to put in tremendous effort physically and mentally to pull it off. Trainer Twight summed it up best saying:

"We're trying to use physical means to basically repair a person or change them in a psycho/physical way, so they can play a role, in this context. You need a guy to look like Superman. It will be better if he feels super, in order to transmit that message."

Comic book Batman vs Superman

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