Alexander Skarsgard has never exactly been a schlub, but his appearance in “The Legend of Tarzan” is … otherwordly. As Conan O’Brien says, “I was hoping that was a computer program because then I can tell my wife, ‘That can’t be done!'”

But it can be done — by doing nine months of training while eating chicken breasts and broccoli. Skarsgard tells O’Brien that they had a chef specially preparing his meals and the chef wanted to spice things up, but … there’s only so much you can do with that kind of diet.

RELATED: Still swinging – the history of Tarzan, from comic books to Skarsgard

“We had a chef, he was a real artist, he really tried to make it interesting … but his hands were tied, he couldn’t use cream, couldn’t use any sugar. None of that, no fast carbs, no pasta, no breads,” says the former “True Blood” star.

Skarsgard says he did get to eat six meals a day, “which is quite a lot,” but the portions were so small that he was “constantly hungry.”

“I had to eat every three hours, which meant I spent the entire day thinking about food. So when I finished a meal, I’d go, ‘Alright, two hours and 59 minutes until my next meal,” he says.

“I would rather dig a ditch!” quips O’Brien.

And then, just when Skarsgard thought he was done, they pulled him back in.

"We wrapped the movie and I fell off the wagon completely and five months later David Barron, our producer, called me and said, 'So we have this little scene we added at the end of the movie that we want to shoot in four months, it's about a five-second scene, so can you go back on that diet for that scene?'"

What did Skarsgard do? "I went back on the diet."

But it's a good thing he got into such incredible shape, because there was one scene in particular that was fairly physically demanding -- the sex scene.

RELATED: Alexander Skarsgard refuses to wear a shirt in 'Legend of Tarzan' trailer

"When we shot the scene, Margot [Robbie] and I, we did the scene and we shot it, but it's like two minutes of missionary position and David Yates, our director, wasn't quite happy with that. I felt it was sufficient, I thought it got the job done ... David was not happy, so he wanted something more primal and slightly more animalistic," says Skarsgard.

If there's a sequel, Skarsgard has an idea that would require a lot less work.

"If we make another one, it could be 10 years after [this movie], so maybe he's out of shape? He's in a hammock the entire movie, he drinks pina coladas."

"The Legend of Tarzan" opens nationwide July 1.

Posted by:Andrea Reiher

TV critic by way of law school, Andrea Reiher enjoys everything from highbrow drama to clever comedy to the best reality TV has to offer. Her TV heroes include CJ Cregg, Spencer Hastings, Diane Lockhart, Juliet O'Hara and Buffy Summers. TV words to live by: "I'm a slayer, ask me how."