The Michael Mann-film, charting life of the founder Ferrari marque, begins shooting in spring and the actor was concerned about gaining the necessary weight in that short of time, said The Hollywood Reporter.
"The Big Short" actor, 41, is no stranger to intense bouts of weight gain and loss for roles, going from an emaciated in his roles like "The Fighter" and "The Machinist" to unhealthily overweight in "American Hustle".
Mann is currently working on re-casting the part so that the springtime shoot can move forward.