Josh Hartnett will soon be seen on the big screen, playing a very bizarre and very dark role in Trap. But, before portraying a serial killer trapped at a concert venue, he was part of the stacked cast of Oppenheimer. With that, he worked alongside great stars like, Cillian Murphy, Emily Blunt and Robert Downey Jr. Hartnett was also able to work alongside Matt Damon on the on the Best Picture winner. And, as it turns out, Damon gave Hartnett some hilarious “advice” when he decided to gain weight to play his role in the historical drama.
Christopher Nolan's Oppenheimer sees Josh Hartnett plays nuclear physicist Ernest Lawrence, who worked with the eponymous Atomic Bomb creator. While promoting his latest film on The Tonight Show Starring Jimmy Fallon, Hartnett talked about spending a lot of time with Matt Damon (a.k.a. “Uncle Matt”), who played Director of the Manhattan Project, General Leslie Groves. During that time spent together on the set, Damon provided some insight on the human anatomy that should've come earlier. During the chat, which is on YouTube, Hartnett explained:
He gave me a lot of good advice. One [piece] in particular — one thing that was just so unhelpful, he told me not to gain the weight I’d already gained for the role. I gained about 30 pounds for the role, and he was like, ‘You’re never gonna get that off again, man.’ Don’t gain weight over 40. He’s like, ‘You’re gonna spend the rest of your life trying to get that weight off, and it’s never gonna come off. Because your body’s gonna want to get that weight back on. And you’re just gonna keep growing back out to that size, and you’re gonna try to get it off, but it’s just gonna grow back. And he just kept telling me over the course of the production, and I was like, ‘Thanks, Matt.’
Yeah, "Thanks, Matt!" Unfortunately, that "advice" was received a little too late. It’s unclear if the Black Hawk Down actor was required to gain weight to play Ernest Lawrence or not. But stars like Joaquin Phoenix and Christian Bale have made intense weight loss and gains for movies to help get into character. While the advice didn't come as soon the Sin City alum would've liked, I’d prefer to believe the Good Will Hunting actor was still looking out for his co-star’s best interests after warning him of the struggle of gaining too much weight for a movie.
For all we know, Matt Damon could be speaking from his own personal experience with changing his weight for movies. While promoting Ford v. Ferrari, Damon talked about losing weight for films, such as the time he brought his weight down to 130 lbs for Courage Under Fire. He lost around 60 lbs. within four months for CUF thanks to the help of a bodybuilder and a new diet. Afterwards though, Damon admitted how unhealthy it was to lose that much weight to film flashback scenes only to have to gain all of that weight back three weeks later. I can't even imagine having to deal with such a situation as a performer.
While Matt Damon’s brutally honest wisdom for Josh Hartnett may have been “unhelpful” as far as Oppenheimer goes, Hartnett can still take that knowledge and apply it to his work moving forward. So I'd say that "Uncle Matt" certainly deserves some credit for trying to help out a fellow actor.
You can check out Josh Hartnett, Matt Damon and more by streaming Oppenheimer, which is available to watch using a Prime Video subscription. Also, make sure to catch Hartnett’s latest creepy flick, Trap, which opens on August 2 amid the 2024 movie schedule.
