How Matt Damon got down to his 'high school' weight for 'Odyssey' role

What diet change helped Matt Damon lose weight for 'The Odyssey'?

Is gluten-free diet effective for weight loss according to experts?

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Read moreMatt Damon trimmed down to his high‑school weight for Christopher Nolan’s upcoming film “The Odyssey” by adopting a strict gluten‑free diet and daily exercise, a change he says he will keep after filming.

For Matt Damon, gluten is not the sustenance of heroes.

The Oscar-winning actor, who stars as Greek warrior Odysseus in the upcoming Christopher Nolan film "The Odyssey," got candid on the diet hack that helped him slim down for the action-hero role during an appearance on the "New Heights" podcast Wednesday, Jan. 7.

"I was in really good shape. I lost a lot of weight," Damon, 55, told cohosts Travis and Jason Kelce. "He said he wanted me, like, lean but strong. It's a weird thing."

Damon attributed much of his weight-loss transformation to completely removing gluten, a protein found naturally in grains including wheat, rye and barley, from his diet with the consultation of his doctor.

"I used to walk around between 185 and 200 [pounds]. I did that whole movie at 167," Damon recalled. "And I haven't been that light since high school. So, it was a lot of training and a really strict diet."

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While demand for gluten-free products is on the rise, in addition to the protein earning a "bad rap" among some online health influencers, dietitian Caroline Thomason previously told USA TODAY that gluten-rich foods such as whole wheat bread and barley are actually "great sources of fiber, B vitamins and prebiotics that can support your gut health."

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"The idea that bread is bad feels right to some people, especially when it's tied to diet culture," Thomason said in July 2025. "Cutting gluten has been glamorized as a quick fix for weight loss, bloating or inflammation. But the truth is, unless you have a medical reason to avoid it, removing gluten won't magically solve those issues."

Although Damon has wrapped production on "The Odyssey," which is slated to hit theaters on July 17, the actor said he's maintained his gluten-free diet.

"I'm done. I'm done. I'm gluten-free everything," Damon said, adding with a laugh, "I found a gluten-free beer. 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."

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Aside from changing his diet, Damon also chalked up his dramatic weight loss to a consistent exercise regimen.

"You know, it's like just part of your day. It's part of your job, right?" Damon said. "And it's like yeah, you get really routinized about it and really kind of build your day around all that stuff."