BEVERLY HILLS, California — There are three things you need to know about "The Cake Eaters," which opens in limited release this weekend:

1. Nobody eats cake in it.

2. The word "cake" is never actually uttered.

3. It might just be the best performance of "Twilight" star Kristen Stewart's young career.

The directorial debut of Hollywood veteran Mary Stuart Masterson, "Cake Eaters" is named for a Southern slang term describing the "haves" — although, for most of the film, Stewart and co-stars Bruce Dern and Melissa Leo depict "have-nots." When we recently caught up with Masterson and her newly A-list leading lady, both agreed that the recent success of "Twilight" has their small film eating cake.

"It's helped," Masterson said of KStew's new fans, who are now clamoring to see the flick. "It only helps to have fans who want to see the people in this movie."

"It's an appropriate story for them," agreed Stewart, who excels in the difficult role of Georgia, a terminally ill teen suffering from the nerve disease Friedreich's ataxia. "[The stories of Georgia and Bella Swan] are like the same thing: You're willing to risk it all for someone. [That quality] is as confident as it is unabashedly human. It's a feminine quality to drop everything and just go for the selfish thing that you want — and [both] definitely do that."

In the film, Georgia falls for ne'er-do-well loner Beagle (Aaron Stanford, "X-Men 3"), risking the wrath of her overprotective mother as she cuts her hair short and decides to lose her virginity to him. Naturally, the decision for an actor to portray a speech-slurring, physically disabled character who often needs to be carried from one room to the next was a dangerous one — so Stewart leapt in headfirst.

"The only way that I could imitate the physical aspects is literally to just do an impersonation; I don't know what it feels like, I could never say that I would," she admitted. "There's more responsibly than just your own self-inflicted care for the character. So I spoke to girls that Mary Stuart put me in contact with [who suffer from Friedreich's ataxia], I got to know their families, one of them specifically a lot. They are so unbelievably brave and honest. ... They are willing to enjoy life, while everyone around them just wants to pity them."

That leads us to one of the more surprising aspects of Stewart's performance: its sexuality. In the flick, Georgia tries to bring awareness to her disease by selling beautiful, black-and-white photos of herself in various states of undress. In real life, Stewart hoped to do the same by portraying Georgia as what those Friedreich's ataxia sufferers wanted to be seen as: normal.

"Do people with disabilities want to have sex?" Masterson said. "Of course. Everyone who is breathing wants to have sex!"

"That was the theme on my particular aspect of the story," Stewart said of the character's urge to live life to the fullest — a lesson that sometimes made the 18-year-old actress consider her own mortality. "If you're going to live however long you're going to live, you have to live and not focus on the negative aspects. And [the sufferers] are so good at that, they have a remarkable appreciation for their lives. It is something to be envied."

Check out everything we've got on "The Cake Eaters."

For breaking news, celebrity columns, humor and more — updated around the clock — visit MTVMoviesBlog.com.