Cillian Murphy Ate Next To Nothing For His Oppenheimer Diet

If the real J. Robert Oppenheimer felt the weight of the world on his shoulders during the construction of the atomic bomb, actor Cillian Murphy shared some of that responsibility as well. After appearing in smaller roles in "The Dark Knight" trilogy, "Inception," and "Dunkirk," Murphy has finally stepped into the very bright spotlight in director Christopher Nolan's heart-stopping historical epic, "Oppenheimer." It's Murphy's first lead role in a Nolan project, and the veteran Irish actor was determined to look the part by whatever means necessary.

To resemble the real-life scientist known as the father of the atomic bomb, Murphy shed a great deal of weight to mirror the striking features and silhouette of Oppenheimer, to the point where he would sometimes forget to eat on set. Nolan shot "Oppenheimer" in only 57 days, and that breakneck pace only added to the intensity of Murphy's performance. "I was running on crazy energy," Murphy told The Guardian. "I went over a threshold to where I was not worrying about food or anything. I was so in it, a state of hyper something. But it was good because the character was like that. He never ate."

Before dying of cancer in 1967, the real Oppenheimer practically survived on "cigarettes and pipes, he would alternate between the two," Murphy noted. Fortunately, that wasn't the only thing on the menu when "Oppenheimer" was filming. However, Murphy's dedication kept him from socializing and dining with the other actors on location in New Mexico, at least according to Matt Damon and Emily Blunt (who play General Leslie Groves Jr. and Kitty Oppenheimer in the film).

During filming in a remote location deep in the New Mexican dinner, all the actors stayed in the same hotel and had dinner together every night. Damon and Blunt recently sat down with Entertainment Tonight, revealing that the experience making "Oppenheimer" felt like being at summer camp with plenty of margaritas at their disposal. Sadly, Murphy was too immersed in character to ever have the chance to sit back and unwind with the rest of the cast.

"We invited Cillian to dinner every night, and he never went," Damon revealed. "He was losing so much weight for the part that he just didn't eat dinner, ever," he said. In what could be an example of overcommitting to a part, Blunt noted that Murphy would usually only eat "one almond most nights or a little slice of apple." 

Both actors understood the pressure Murphy was under to deliver a crackling performance, telling People magazine that there wasn't any opportunity to downshift. "The sheer volume of what he had to take on and shoulder is so monumental," said Blunt. "Of course, he didn't want to come and have dinner with us."

Now that Murphy has the chance to really shine in "Oppenheimer" after literally wearing a sack over his head as the villainous Scarecrow in "Batman Begins," he has wisely not revealed exactly how much weight he actually lost for the role. "I don't want it to be, 'Cillian lost x weight for the part," he admitted. The story should rightly be focused on his breakout lead performance, not his almost non-existent diet.

"Oppenheimer" is now playing in theaters.