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Jennifer Garner stepped onto the red carpet last night to debut her post-baby body and revealed one tip for looking so good just six months after she and husband Ben Affleck welcomed their son Samuel.

Garner -- who was attending the New York premiere of her new comedy Butter -- said her biggest tip to keeping her fabulous body looking slim and trim is to "double up on the Spanx."

VIDEO: Exclusive Clip of Jennifer Garner's Butter

Butter -- also starring Hugh Jackman, Ty Burrell, Olivia Wilde, Ashley Greene, Alicia Silverstone and Rob Corddry -- showcases the wildly competitive and sometimes wacky world of butter carving. The movie is currently on VOD and iTunes and hits theaters October 5.

Modern Family star Burrell also attended the premiere -- which was sponsored by the Cinema Society with DKNY, diamond maker Forevermark and RentTheRunway.com. Burrell talked about his co-star Sofia Vergara's wardrobe malfunction at last Sunday's Emmy Awards and also discussed his role in the film playing the husband of Garner's character Laura Pickler.

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Greene recounted a steamy make out scene she has with co-star Olivia Wilde, who plays a stripper. "I think we just kind of dove into it, because you can't over think something like that," she revealed. "I think that's what makes you nervous. It's such a fun, quirky, outrageous film that we kind of had to make that as outrageous in it's own right -- so we just had fun with it."

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Watch the video for more red carpet interviews, including Wilde's explanation of where she drew inspiration for her stripper portrayal.