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Jennifer Lawrence admits that she never knows "what's going to come out of my mouth," and so was the case during her interview with ELLE magazine. The Hunger Games actress opened up about everything from body image to her relationship with British actor Nicholas Hoult.

Lawrence had some intense training for her role as Katniss, but tells the magazine that she was always healthy. "I'm never going to starve myself for a part… I don't want little girls to be like, 'Oh, I want to look like Katniss, so I’m going to skip dinner,'" she explains. "That's something I was really conscious of during training, when you're trying to get your body to look exactly right. I was trying to get my body to look fit and strong- not thin and underfed."

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The outspoken actress, 22, also couldn't help but gush about her boyfriend and X-Men: First Class co-star, 22-year-old Hoult. "[My boyfriend] is honestly my best friend, and hopefully I'm his best friend too," she confesses. "He's my favorite person to be around and makes me laugh harder than anybody…We can eat Cheetos and watch beach volleyball and we turn into two perverted Homer Simpsons, like, 'Oh, she's got a nice ass.' I never thought we'd have such different opinions on asses."

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As for saying what she thinks, Lawrence isn't so proud of that attribute. "When I get older, I'll be more mature and poised. And I'll have control over my mouth. One day, I'm going to grow up…When we leave, I'm going to have a knot in my stomach. I'm going to be like, 'Oh, did I say something wrong? I'm going to get in trouble!'"

Lawrence covers the December issue of ELLE, on newsstands November 13.