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Kim Kardashian

Michael Buckner/WWD/REX/Shutterstock

Earlier this week, people began speculating thatKim Kardashian digitally altered herself for her appearance in Fergie's "M.I.L.F. $" music video...but the truth is, the reality star has been toning up more and more over the last few months through hardcore working out and dieting.

In fact, a source tells E! News that Kim has lost 7 lbs. in the last two weeks, and she's not stopping there! She is aiming to lose even more weight in order to get down to at least 120 lbs.

So how is she going about it? "She's been working out twice a day, cardio and then a class like Pilates," the insider explains. "And she's doing a very strict Atkins plan, eating about 20 grams of carbs a day. She's really happy with the results."

And since she's been working so hard, Kim was not about to let the haters speculate that she uses photoshop to enhance her body. She did, however, admit to wearing a corset for it.

She took to Snapchat Sunday night to set the record straight, posting a behind-the-scenes video—which she shot in May—from the "M.I.L.F. $" shoot, wearing a crop top and high-waisted shorts. "F--kYoPhotoShop #Corsetlife," she wrote.

Corset aside, however, Kim has been going hard in the gym and always keeping her fans updated on her weight loss, continuously posting photos of her scale on Snapchat as she dropped the pounds.

Kim Kardashian, Fergie M.I.L.F. $ Video

Interscope Records

Part of her motivation came when she found out she was shooting the cover of GQ's 10th annual "Love, Sex & Madness" issue. "I woke up every day at 6 in the morning and worked out. I did a strict Atkin's diet. Strict, strict, strict," she told WWD of getting ready for the shoot. "It was really hard for me to diet [with the] first baby [North West]."

She continued, "This time was so much easier and I realized [it comes down to] the food. I mean, I love to work out and you definitely have to work out to tone up, but so much of it is how you eat. I had to really stay focused. I had to cut out all the sweets and I had such a sweet tooth," she said. "After-baby body? I welcome that challenge. It's so crazy to see what your body can go through and what it's capable of."

Stay tuned for more from Kim on the newest episode of Keeping Up With the Kardashians, Sunday at 9 p.m.