Matt Damon reveals diet secret behind major weight loss

Matt Damon got candid about one diet swap that transformed him to be lighter in decades.

During an appearance on Wednesday's episode of the New Heights podcast, the 55-year-old talked about how he changed his physique for his recent role in The Odyssey.

"I was in really good shape. I lost a lot of weight. He said he wanted me like lean but strong. It's a weird thing," Damon said, referring to the film's director, Christopher Nolan.

"I literally, just because of this other thing I did with my doctor, stopped eating gluten," Damon revealed.

The cut-off for the movie criteria helped the star, who was around 185 and 200 pounds, to reach 167.

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

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

The actor remarked that he has been on a gluten-free diet since then. "I'm done. I'm done. I'm gluten-free everything," Damon said.

For the unversed, a gluten-free diet eliminates gluten, a protein found in grains such as wheat, barley, and rye. It is used to manage different digestive conditions.