Dwayne 'The Rock' Johnson 's incredibly thin figure has Hollywood buzzing, and the former WWE superstar has yet to reveal what exactly he did to lose all of his muscles and weight, RadarOnline.com can reveal.

However, a weight expert exclusively told us what the actor may have gone through for his new body, and how she hopes he did it the healthy way. Article continues below advertisement

How Did Johnson Transform His Body?

"To train for a role like Mark Kerr in The Smashing Machine , there needs to be a lot of guidance and/or knowledge on how to put on muscle like that healthfully," Toby Amidor , MS, RD, award-winning nutrition expert and best-selling author of Health Shots , told RadarOnline.com .

Johnson transformed his body to portray to mixed martial artist

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