‘The Odyssey’ star Matt Damon reveals strict diet choice that 'changed my life' after hidden health issues

Matt Damon's dramatic transformation for "The Odyssey" came with an unexpected payoff.

The Oscar winner revealed during the latest episode of Amy Poehler's "Good Hang" podcast that he has permanently cut gluten from his diet after discovering how much it had been affecting him, calling the change life-altering as he underwent an intense physical transformation for Christopher Nolan's upcoming epic film, "The Odyssey."

"It's just a complete, complete lifestyle change," Damon said of, as Poehler described it, "getting jacked in your 50s."

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"There's no planning it. Any other time I tried to do something like that, it was always like, well, ‘My time, my workouts’ … and this was like … just put your foot on the gas and that's it. And that's the only way to do it, and eat a little less," he said.

Damon added that he cut out gluten, "which changed my life."

When Poehler asked whether he still had "any desire" for it, Damon replied, "No, because of what it does to me … I didn't know."

Poehler noted that many people in their generation weren't aware of food sensitivities while growing up.

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Damon agreed, saying, "We didn't talk about it, and I didn't realize the level to which it was affecting me. Like it's completely changed my life these last couple years of not eating it … it's a bummer. I'm a big fan of bread and beer, and pasta and pizza and all that stuff, but … how I feel is just [so much better.]"

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Earlier this year, Damon detailed the grueling regimen he followed to play the legendary Greek hero Odysseus in Nolan's highly anticipated adaptation of "The Odyssey."

Speaking on Travis and Jason Kelce's "New Heights" podcast, Damon said he dropped to 167 pounds — his lightest weight in decades.

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"Yeah, I was in really good shape," Damon said. "I lost a lot of weight."

Nolan had a specific vision for the character.

"He said he wanted me … lean but strong," Damon explained.

The actor said eliminating gluten played a major role in the transformation.

"I literally, just because of this other thing I did with my doctor, stopped eating gluten," he said. "I used to walk around between 185 and 200 pounds. And I did that whole movie at 167 pounds."

"I haven't been that light since high school," Damon added. "So it was a lot of training and a really strict diet."

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Damon also credited working with a personal trainer for helping him stay focused throughout the demanding process.

"Trainers are like, 'What are we doing?' And they can kind of do anything," he said. "It's just having kind of a clear goal and setting it."

The transformation wasn't the first of Damon's career.

For the 1996 war drama "Courage Under Fire," he shed between 40 and 50 pounds in about 100 days — a drastic weight loss he later revealed nearly came with an extreme cost.

According to Damon, a doctor warned him he "could have shrunk my heart permanently."