Kim Kardashian Instagram Bikini Photo: "Keeping Up With the Kardashians" Star Tweeted Pic of Post Baby Body / Kanye West Responds [PHOTO]

Kim Kardashian is looking as good as ever after the birth of her first child North West earlier this year. She tweeted an Instagram picture yesterday that revealed her famous backside to show how much she had slimmed down since the birth of North.

Kim has been on the Atkins diet since the birth of her first daughter and it has helped her lose the baby weight. A rep for Atkins said, "She is eating lots of lean proteins, healthy fats like nuts and avocado, carbs, fruits, veggies and cheese. She wanted to be a healthy, nursing mom and not toxify her milk with her diet or lose weight too quickly. She's been doing Atkins since her doctor approved it at the end of June."

Her current boyfriend and the father of her daughter North, Kanye West, has been seen with Kim at various workout locations as the two sweat it out together.

Kanye tweeted back at Kim after she shared the photo, saying, "Heading home now!"

Kanye has been busy trying to get Kim a star on the Hollywood Walk of Fame even though she doesn't meet the qualifications.

Kim told Du Jour Magazine, "My boyfriend has taught me a lot about privacy. I'm ready to be a little less open about some things, like my relationships. I'm realizing everyone doesn't need to know everything. I'm shifting my priorities."