Kim Kardashian Shares Bikini Selfie She Almost 'Forgot' to Post

As one of the reigning queens of Instagram, Kim Kardashian knows what the people want, and the reality personality delivered Tuesday morning with a classic mirror selfie.

In the snap, the mom of three donned a black bikini and large rhinestone choker, wearing her blonde hair down in a long bob as she gazed at her phone's screen.

"Forgot to post this last night," she wrote.

In a new video posted to her app on Feb. 12, Kardashian spoke to her sisters about her tiny figure, sharing that she had slimmed down to a size 24 waist.

The clip, which was a behind-the-scenes peek of the mom of three's book club, saw sister Kourtney Kardashian comment on the size of Kim's waist versus the size of her hips.

"I can't take your hips seriously right now...because your waist is so small and then your hips are so big," Kourtney said.

Hairstylist Jen Atkin had Chrissy Teigen guess the size, and while Teigen was close at 23 inches, Kim told the women that her waist size was a 24.

"It's never been 24 ever in my life," Kim said, adding that her hips were 39 inches.

Over the past year, Kim has been working with trainer Melissa Alcantara to seriously sculpt her figure.

"Kim told me, 'I love my body. I love the way it looks and I love my hips,'" Alcantara recently told People. "She just wanted more muscle. She wanted bigger hamstrings, which accentuates the entire leg. And she wants those cut arms and abs!"

Alcantara puts Kim through workouts at the makeup mogul's home six days a week at 6 a.m., and also helps the star eat healthy, working with Kim's chefs to plan a diet promoting a healthy balance of proteins, carbohydrates and fats.

"Kim has been getting some really nice results, like with her triceps! She can't believe how much has changed over the last few months," the trainer shared. "And when you're in this deep, it's hard to go back. She just keeps it up. She's focused and she has a goal in mind."

Photo Credit: Instagram / @kimkardashian