Mark Wahlberg can certainly appreciate a good cinematic physical transformation. But the actor, who regularly chronicles his fitness journeys on social media, tells EW his weight gain for Father Stu took a significant toll on him.

In director and writer Rosalind Ross's latest film, Wahlberg play Stuart Long, a bad-boy amateur boxer whose career is destroyed due to an injury. When he moves to Los Angeles in pursuit of stardom, he ends up falling for a Catholic Sunday school teacher. Coupling his budding relationship with the aftereffects of a devastating motorcycle accident, he sheds his agnostic beliefs and sets out to become a priest.