Lily James gushes over Zac Efron transformation: ‘incredibly muscly’

Pam & Tommy actress Lily James revealed how she was left surprised by Zac Efron’s incredible body transformation.

James, 33, who is starring alongside Efron in the upcoming movie The Iron Claw said she even struggled to concentrate on the set of the film.

"[He had] a great bowl cut, but he was also incredibly muscly which was slightly more distracting."

James added further, "But what was more incredible is his performance, he has really transformed."

Many fans of the actor were left stunned last year when he was spotted backstage completely unrecognizable.

The 35-year-old actor debuted his new look while he was strolling around on the set of his film in Louisiana, dressed in a knitted grey tank top and skin-tight denim cut-off shorts he flaunt his super-tanned, toned legs.

He sported a very square-looking pudding bowl-style haircut in the images, which was far beyond his original clean haircut.

The Greatest Showman star body was also fully transformed with giant muscles and a chiselled six-pack.

Efron is playing the role of sixties famous wrestler Kevin Von Erich in The Iron Claw, that follows the Von Erich family, who were wrestling icons in their 1960s heyday - but went on to be tormented by tragedy after tragedy.

The sportsman is now 65 years old and was a one-time world champion, having won the WCWA World Heavyweight Championship.