Actor Matt Damon, 55, has been an action star for quite a few decades at this point, but he still needed to get into serious shape for his upcoming role.

Damon is set to lead in Christopher Nolan’s film Odyssey, as character Odysseus and had to shed a few pounds for the character.

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Speaking to Jason and Travis Kelce on their New Heights podcast on January 7, Damon revealed how he did it.

Jason started by saying some of the early shots of the film that are circulating on social media show Damon looking ‘pretty yoked up’.

Damon explained he got into ‘really good shape and lost a lot of weight’. He also compared the prep to how the pair would prepare for games in the NFL.

Damon explained he lost as much as 30 pounds for the role (New Heights/YouTube)

He explained that it eventually becomes a part of the day, and ultimately being in the shape necessary to do your role is part of your job.

Explaining the dieting aspect, Damon said he cut out one thing which just happened to coincide with something he was considering with his doctor.

He said: “[Nolan] said he wanted me lean but strong, and so its a weird thing, I don’t want to bore the s*** out of you but I literally, just because of this other thing I did with my doctor, stopped eating gluten.

“I used to walk around at between 185 [pounds] and 200 and I did that whole movie at 167. I haven’t been that light since high school.

“So it was a lot of training and a really strict diet.”

Gluten is a protein found in wheat, rye, barley and many other processed foods, including pasta, breads and cereals.

Some people avoid gluten because they have Celiac disease, a disease that happens when the body’s immune response to gluten damages the small intestine lining, according to the Cleveland Clinic hospital.

Whereas other people avoid gluten because they are intolerant to it.

Despite Damon’s comments, however, doctors have long dismissed the idea that removing gluten from a diet will result in weight loss.

Cleveland Clinic noted: “There’s absolutely no evidence that simply getting rid of gluten will result in weight loss. But if you eat a gluten-free diet you may make healthier food choices because you’re more aware of how to read food labels.

“Eating gluten-free often may cause you to eat more whole foods such as fruits, vegetables, legumes, and lean meats. These diet changes are often healthier and lower in calories.”