Matt Damon underwent a major weight loss transformation before filming The Odyssey. "I was in really good shape. I lost a lot of weight," Damon, 55, said on the Wednesday, January 7, episode of the "New Heights" podcast, noting director Christopher Nolan wanted him to look "lean but strong" to portray iconic hero Odysseus. "I literally stopped eating ... gluten." According to Damon, he "used to walk around at between 185 and 200" pounds but slimmed down to 167 for The Odyssey. "I haven't been that light since high school. It was a lot of training and a really strict diet," the Oscar winner said. "I have [a trainer, but they] are like, 'What are we doing?' They can, kind of, do anything. It's just having a clear goal and setting it." Celebrities Who've Lost or Gained Weight for Movie and TV Roles Damon considers his training to be "a part of [his] day" and job. "You get really routinized about it and build your day around all that stuff," he said. "That's kind of the physical side of getting ready." In addition to spending time in the gym, Damon also adopted a gluten-free nutritional plan. "I'm gluten-free everything. I found a gluten-free beer," he said. "It's been so long since I've had gluten, I can't tell if it's good or not, so that's a good sign." The Odyssey is adapted from Homer's poem of the same name about Odysseus' 10-year journey home from the Trojan War. The film also stars Anne Hathaway, Tom Holland, Robert Pattinson, Lupita Nyong'o, Zendaya, Charlize Theron, Mia Goth and more. "I'm a fan [of Christopher Nolan]. I just love the movies that he makes and also just the way he insists on shooting them," Damon teased of the film production. "This one was 100 percent on IMAX. It was the first movie that was ever done all on IMAX, like, IMAX cameras are really loud. It sounds like a blender [or] a Cuisinart in your face." Celebrities' Weight Loss Transformations: Photos of Jelly Roll and More Because of the noisy camera, the actors weren't able to film dialogue scenes like normal. "They built this giant thing around the IMAX for those dialogue scenes and a system of mirrors so your eyeline would be close to the camera and you could talk to the other actor," Damon said. "The amount of work that went into figuring out how to do 'cause he wanted to do it 100 percent IMAX, and he did it. It's, like, a really ambitious kind of idea that he has on the technical side." Damon continued, "Then, there were locations that we went ... where we would get there and I'd just start laughing. I'd be, like, 'Nobody has any business shooting here, but of course he wants to shoot here.'" Damon further praised Nolan's "great crew" for putting together the ambitious epic. "His crew is so badass and everybody just maxed out on that movie and we made all of our days. We actually finished ahead of schedule," he said. "It was an awesome experience, [but] it was just an awesome experience. I haven't seen it yet."