The True Blood star was restricted to a "horrible" diet throughout filming so he'd look lean and mean as the literary ape man, and he tracked down his actor dad Stellan once he'd completed work on the movie and enjoyed a blow-out meal.

"The diet was horrible," he tells WENN. "I gotta give credit to our chef who really tried to make it OK; he's an amazing chef but he had his hands tied with no sugar, no dairy...

"When we wrapped the movie my father was shooting River, this Netflix mini-series in London at the time. I got in my car and went straight to his house. My dad loves to cook and I spent four days on his couch just being fed! It was the most incredible weekend of my life. It was a bone marrow, fried mozzarella, pasta, red wine."

To look ripped as Edgar Rice Burroughs' Tarzan, Alexander also had to hit the gym and work with celebrity choreographer Wayne MCGregor.

"The first phase was three months of bulking up while I was still shooting True Blood," he explains. "I was eating 7,000 calories a day of steak and potatoes and weightlifting. When I got to London about a month and a half before we started the movie I had a great opportunity to work with Wayne MCGregor, who is one of the best choreographers.

"It was my best experience working with Wayne on the physicality of the character. Tarzan was flexible and agile when he moves through the jungle, and he doesn't look like a bodybuilder. So even though I wanted to put on some weight the goal wasn't too get buff, but to look athletic."