Speaking on Variety's podcast, Just for Variety, recently, the actor explained how he began eating meat when he first came to America in order to transform his body.
WATCH: Have you caught up on the latest Outlander episode?
"I grew up a pescatarian, or sort of vegetarian-pescatarian," he said. "I didn’t start eating meat until I came to America when I was 24."
Explaining what prompted him to change his diet, he told host Marc Malkin: "At the time I was auditioning for Superman, and I had a trainer and they were like, 'You need to get bigger, you need to be able to fill out the cape', he was like, 'Eat more protein.'"
He continued: "I remember the first time I had chicken and suddenly I was like, 'Oh my God, I have all this energy and I don't feel hungry all the time.'"
Sam underwent a major change before starring in Outlander
Chatting about how far he got in the audition process for the 2006 Superman Returns film, he clarified: "The movie, it was the Brandon Routh one, it was way back then. I did a number of auditions, met the producers, but we never screen-tested or anything."
He added: "It was the beginning of me sort of coming to America I guess and the audition processes, and I realised I needed to change my body shape for the sort of roles I was going up for."
Sam stars as Jamie Fraser in the period drama
The 41-year-old is currently starring in the hotly-anticipated sixth season of Outlander, which began airing at the beginning of March. The latest series saw Sam and Caitríona Balfe reprise their roles as Scottish highlander Jamie and his wife Claire.
Season six follows the married couple as they strive to protect their new home in colonial America during a period of political unrest leading to the Revolutionary War.
Outlander is available to watch on all Starz platforms.
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