Movies

Aaron Eckhart loses the fat, cigars for ‘I, Frankenstein’

He’s not your 19th-century Frankenstein.

“I don’t know where this lumbering idiot came from. In the book, he’s extremely articulate, he’s sensitive, he’s a quick learner,” Aaron Eckhart tells The Post. “I mean, Frankenstein has gotten a bad rap.”

The 45-year-old actor gave the monster a makeover for the gritty new action-fantasy film “I, Frankenstein,” in theaters Friday. In the movie, based on a graphic novel, Eckhart stars as Adam, Dr. Frankenstein’s chiseled monster. Caught in a centuries-old battle between gargoyles and demons, he’s not green, nor does he have bolts in his neck.

“This is so different,” says Eckhart, explaining why he was drawn to reinterpreting the classic character. “We’re kind of the next chapter in terms of what would happen if he were roaming the Earth forever. How does a man who’s been cast out by his father, called an abortion — an aberration — now trust somebody?”

The other big difference? This time, the monster has a killer six-pack.

Although Eckhart says, “I haven’t been to the gym in years,” don’t think he hasn’t suffered for his art. “I work out every morning — I throw rocks and dig holes and jump over stuff [and] I’m also a road cyclist.”

He also quit cigars this year after coming down with pneumonia — ironic, given that one of his most lauded performances was as a tobacco lobbyist in “Thank You For Smoking.”

And then there’s his diet.

“Yesterday, I was doing some shopping and I had to tear myself away from getting a large pizza,” he says. “I literally had to wrench myself out of the pizza place. I didn’t eat at all until I got home — I had put some yams in the oven earlier that morning. So I had cold yam.”

Eckhart was born the youngest of three brothers in Cupertino, Calif., to a Mormon family. (“I’m Mormon. I grew up Mormon,” he says of his faith today. “You [always] have those ideals inside of you.”) The Eckharts eventually moved to England, where Aaron got his start in acting as a teenager, playing Charlie Brown in a school production. After that, he never stopped.

His big break happened in 1997, as the lead in

Neil LaBute’s “In the Company of Men,” but name recognition came from playing Julia Roberts’ biker beau in 2000’s “Erin Brockovich.” Ever since, Eckhart has appeared in a blend of critically acclaimed indies (“Rabbit Hole,” “Thank You For Smoking”), explosion-fests (“Battle: Los Angeles,” “Olympus Has Fallen”) and even superhero epics (playing Harvey Dent/Two-Face in “The Dark Knight”).

That last one inspired him to keep “Frankenstein” from veering into dangerous camp territory, unlike many other graphic novel adaptations.

“You just gotta take it really seriously, which I did,” says Eckhart. “It’s like ‘Batman.’ You know, some are more campy than others. And why are they? It’s the director, really. People like Chris [Nolan] taking the initiative or making the decision to say, ‘Okay, this is about real crap.’”

These days, Eckhart is also thinking a lot about the messages that his movies send to young kids, which raises the question of whether the bachelor is finally considering a family of his own.

“Yeah, I’m sitting on my ranch in Montana and I’m saying, ‘I have to.’ I do want to have kids,” he says. “I just can’t seem to do the other thing first . . . you know, find somebody to have them with. I’m continually on the lookout.”

He may have difficulty finding the time to do so. Later this year, he’ll star in the supernatural thriller “Incarnate.” Eckhart’s also set to appear in “London Has Fallen,” the sequel to last year’s surprise hit, “Olympus Has Fallen.” He hasn’t read a script, but hopes he’s “kicking somebody’s ass” and “not being tied up to a freakin’ balustrade” like in the original.

But his long-term plan is to create his own works. Over the past two years, Eckhart’s written and produced a movie based on a best-selling book — he’s coy on spilling the details on what it is just yet, other than that it’s an action film about a father and a daughter.

“I think the next step for me is to emancipate myself from [being a] for-hire actor. I’d like to be developing and directing my own movies, and doing what I want to do — and maybe have started a family,” he says. “That’s really the two things that I haven’t accomplished.”