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Miley Cyrus may only be 16, but she's a pro when it comes to staying on message. On Sunday, the Disney powerhouse attended church with her family and her 20-year-old model-boyfriend, Justin Gaston, a spiritual excursion that comes on the heels of her latest vow to earn the right to don white on her wedding day.

"I want to keep my virginity until I marry," the purity ring-wearing starlet reiterates to the London Daily Mail. "I was brought up in a Christian family."

And even though Britney Spears and Jessica Simpson made similar pledges, with mixed results, Miley isn't naïve about the potential pitfalls of fame.

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"It's hard growing up in the spotlight and I'm changing. I can't be the 12-year-old who just moved to L.A. forever," she says. "I'm having a great time doing what I do, but I'm also going to stumble and fall. Having my parents close helps."

And the support of a double Oscar winner doesn't hurt, either.

"People mention child performers who have gone off the rails, but there are also stable people like Jodie Foster," Cyrus points out. "She was a child star and look where she is now. She called to give me advice, which was great."

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Perhaps one tidbit Foster passed along was to maintain a strong sense of self, because Hollywood is a tough town that gobbles self-esteem like candy.

"It's harder finding people who are real," acknowledges a world-weary Miley. "You don't know what's real and what's fake in this city because almost everyone has a motive and everyone wants to get something."

That includes getting the already teeny-tiny Miley to -- geez -- slim down.

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"People will say things like, 'You've got to lose weight and be this smaller size to wear this dress,'" she sighs, before adding, "It's upsetting, but I'm happy with how I look."

Next: Scarlett's majorly mixed reviews