The internet has been alive with speculation over pro wrestler-turned actor Dwayne Johnson’s dramatic weight loss.

Finally the performer – best known to fans as “The Rock” – has revealed the reason for his slimmed-down appearance, and it has taken many by surprise.

Johnson won praise for his performance as real-life US MMA fighter Mark Kerr in movie The Smashing Machine when it premiered at the Venice Film Festival last week.

But it was Johnson’s seemingly gaunt appearance as he greeted fans and media at the festival that sent social media into a spin.

This week, the actor confirmed he was furiously shedding the kilos for a movie – in which he will play a septuagenarian called “Chicken Man”.

The film, Lizard Music, will reunite Johnson with his The Smashing Machine director Benny Safdie in a role he jumped at the opportunity to play.

“Benny pitched me this after [The Smashing Machine],” Johnson said during a talk at this week’s Toronto Film Festival.

“After about 45 minutes, this pitch ended and I said, ‘I am your Chicken Man’.”

The 193-centimetre performer said he had already shed much of the 14 kilograms in muscle he built up to play fighter Kerr.

“I still have a long ways to go,” he said.

Johnson built up muscle to play Kerr in The Smashing Machine. Photo: A24

Lizard Music is an adaptation of a novel by US children’s author Daniel Pinkwater and tells the story of a 70-something man whose best friend is a 70-year-old chicken.

Johnson, 53, said he was excited to extend his range and move away from his action hero image after many years starring in blockbusters such as the Jumanji series, Fast Five and Black Adam.

“I’m so excited to get a chance to hopefully transform again like I was able to do in Smashing Machine,” Johnson said.

“[It means] eating less chicken.”

Johnson has been mooted as an Oscars contender for his role in The Smashing Machine, which offers a gritty look at Kerr’s life, including his toxic relationship with his girlfriend (played by Emily Blunt) and substance abuse struggles.

Fans of The Rock’s big-budget action movies need not fear, however, with Johnson slated to begin filming for Jumanji 3 in November

“The films that I made in the past, I love them,” he said. “I’ll go back to making them again.”