Kim Kardashian reveals how she lost her post-baby weight

New mom Kim Kardashian has revealed the secret to her post-baby body.

“I’ve actually been doing the Atkins diet & luv it,” she said Sunday in a message to her 18 million Twitter followers.

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Her tweet was in response to a fan’s question about how “she’s lost so much weight” in the four months since the birth of her daughter with rapper boyfriend Kanye West.

Atkins is the original low-carb diet, casting out processed foods in favor of lean meat, eggs, dairy, fresh veggies and fruit – and eventually grains such as brown rice and whole wheat pasta.

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It teaches that our bodies convert carbs to glucose and glucose to fat – and that we have no choice but to burn stored fat when carbs aren’t such a plentiful source of fuel.

A rep for Atkins told the Daily News that Kardashian started the diet in Phase 2 – instead of the more restrictive Phase 1 – because she was nursing.

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Kim Kardashian leaves Casa Vega with her baby girl, North, and BFF Jonathan Cheban.

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“After she delivered her baby on June 15, she wanted an effective and balance way to lose the baby weight. She’d done Atkins before and knew it worked, so once she got the approval of her doctor, we connected her with our Vice President of Nutrition Colette Heimowitz, who counseled her directly,” Jennifer Livingston, a spokeswoman with Atkins Nutritionals, told The News.

“Being a new nursing mother, she needed adequate calories to be healthy for her child and keep up her milk production. What’s great about Atkins is that it’s not about counting calories or depriving yourself,” she said.

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Livingston said Kardashian has been eating “tons of lean, nutritious foods such as fish, lean cuts of beef, leafy greens, broccoli, spinach, nuts, avocados and olive oil.”

“It’s a very balanced way for her to loose the baby weight while continuing to properly care for her daughter,” she said.

Kardashian, 32, stepped out Saturday night wearing skinny jeans and a loose-fitting white top for a dinner with pal Jonathan Cheban.

Her precious daughter North was snuggled up in a covered car seat.

During a recent trip to Paris for Fashion Week, the newly blond “Keeping Up with the Kardashians” star wore a series of revealing outfits including a cleavage-baring black gown and more skinny jeans with a plunging denim top.

ndillon@nydailynews.com