Kim Kardashian revealed that she has lost 30 pounds since son Saint West's birth on December 5.

The 35-year-old reality star made the announcement on Twitter after writing that she will partner with Atkins to shed the additional baby weight.

"I'm so excited! I'm 30 lbs down today but 40 to go! I'm so focused. I will show u guys my workouts on my app & share my Atkins plan too!" the star wrote. "I gained 60lbs during my pregnancy but have been an extra 10lbs up for the past few years so it's time to really get to my goal."

Kardashian's significant weight loss alarmed some fans, while others praised her dedication. The reality star previously told fans she was looking forward to hitting the gym and regaining her figure in a post on her website prior to Saint's birth.

"As much as I really hate the whole feeling of being pregnant, I enjoy the challenge of getting my body back after it's all over," she wrote. "I feel so accomplished when I'm back to where I want to be."

Kardashian and husband Kanye West are also parents to 2-year-old daughter North West. Model Chrissy Teigen, who is pregnant with her first child by husband John Legend, shared Kardashian's maternity fashion advice in the February issue of InStyle Australia.

"She told me to go stretchy," Teigen said. "I always wanted to be the person who showed off the bump because it looks beautiful and I think you should embrace it. Kim does that well and I love seeing that belly of hers and I know Kanye does too."

Kardashian shared a photo of North with her cousin Penelope Disick this week, writing, "Real friends." The television personality and her family continue to star on E! series "Keeping Up with the Kardashians," which airs Sundays at 9 p.m. ET.