The British actor had to lose a significant amount of weight to play Eric Lomax, a British Army officer who was sent to a Japanese prisoner-of-war camp in 1942, in the drama 'The Railway Man' and admits his extreme weight loss plan gave him terrible hunger-induced nightmares.
He told Britain's In Style magazine: "It's called the 'no-more-than-one-can-of-tuna-a-day-diet.' I lost almost two stone (28lbs). You're so hungry the whole time you lose your mind a bit. I had no energy and kept having really mad dreams, which alarmed my parents slightly. We had a dietician on set to keep an eye on me.
"For someone of my generation, it's impossible to relate to what prisoners of war went through. I owed it to Eric to make it look as realistic as possible."
However, the handsome 24-year-old star more than makes up for it when he returns to his London hometown, where he regularly binges on junk food with his housemate.
Jeremy said: "When I am in town, my flatmate and I like to do the man version of a dinner party. We cook crappy junk food or whatever you can make in a microwave and call it a 'do'."