Les Miserables was never meant to be a joyous affair. It's very name 'The miserable ones' says that quite strongly, and it's a trope that has been used in other literature, notably in Bret Easton Ellis's American Psycho in which the stage production's posters are referred to repeatedly throughout the narrative to reinforce the melancholia of the novel as a whole. So it's no surprise Anne Hathaway found the whole ordeal fairly difficult.
Miss Hathway played Fantine who suffers from tuberculosis while being forced into resorting to prostitution and selling her own hair to be able to pay for the care of her daughter, born out of wedlock. Not a happy story. Hathaway had to lose a lot of weight for the role to look truly sickly. She refuses to answer questions about how she lost the weight, and told Access Hollywood, "I don't answer that question. Not to like get super serious about it, but just there's so many people out there that will try something unhealthy to lose weight... I don't want to contribute to that."
Not only does it show her to be an empathetic creature, but also implies that the experience for her was a painful one. She's a vegan so her relationship with food is undoubtedly an important one, and she revelled in the food she's been eating since- and for her first post-fast meal: "I had spelt pasta with garlic oil and like a lot of beautiful fresh tomatoes and then I had a twice baked potatoes, with basil sun dried tomatoes [and] oil. It was so good." Yum!
Matthew McConaughey's weight loss has shocked everyone, stepping out looking half the man he once was. His weight loss is also for a role in The Dallas Buyer's Club as an AIDS sufferer. It's not unheard of for actors to lose or gain a great deal of weight for a role: Robert De Niro gained 27lbs for his role in Raging Bull, Christian Bale lost 62lbs for his role in The Machinist, according to the Telegraph, starving himself for four months prior to filming, and Renee Zellwegger gained 20lbs for her role in Bridget Jones' Diary.