Mark Wahlberg dropped sixty-one pounds for his role, going from one hundred ninety-eight pounds to one hundred thirty-seven pounds, by doing a diet consisting of mostly liquid food and vegetables, and a workout of strictly cardio. Wahlberg claimed that he deliberately set one hundred thirty-seven pounds as his goal, because the thinnest he had ever been for a role previously was Boogie Nights (1997), in which he played a teenager, and weighed one hundred thirty-eight pounds.
Each day Jim's shirt color gets lighter, starting with a black shirt and ending with a white shirt
Mark Wahlberg said that he would prepare his whole life for a role like this. However, he said he would never lose that much weight again for a role.
Mark Wahlberg stated that this role was the most challenging of his career.
Mark Wahlberg was determined to nail the role of a literature professor, so much so that he sat in on many college courses around different colleges in California and analyzed many professors and their mannerisms so that he could achieve the most believable performance.