Keep it tight! Kim Kardashian revealed the reason she always feels so confident in her famously skintight ensembles: She wears not one, but two body slimmers.

"Sometimes I wear two pairs of body shapers on top of each other — especially when I am heavier, I def double it up," the Keeping Up With the Kardashians star, 35, wrote via her app.

She added, "They really hold you in and make you feel secure!"

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The mom of North West, 2, and Saint West, 4 months, also shared her three favorite shapers: Body Wrap The Catwalk High-Waist ($42), Spanx Higher Power Capri ($26) and Spanx Higher Power Short ($38).

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"I put one pair on after the other, and if there's a longer pair, I always put those on first," Kardashian explained. "But usually, I wear two pairs that are the same length. I try not to layer two different lengths, because I don't want there to be visible seams; I want there to always just be one seam."

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To truly drive the point home, Kardashian even pointed out a Spanx faux pas she had back in June 2014. "You can actually see my Spanx line right above my knee, and I usually don't like that," she wrote, referencing the photo (above). "I just recently got introduced to the footless tights, which I can wear with longer dresses like this—so you'll NEVER see my Spanx line because the seam is lower. I typically like them past the knee or right at the knee."

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