Rock talks weight loss! If you're anything like us, you've been marveling at Dwayne 'The Rock' Johnson's incredible physical transformation to portray grappler Mark Kerr in the film The Smashing Machine. Fans have been marveling at how much the Rock has slimmed down in order to get into character for that flick about Kerr's UFC-fighting prowess. But the former college football star isn't done losing weight.