The 34-year-old, who welcomed son Saint West in December, took to Twitter to share the astonishing weight loss – but insisted she’s not finished.

Kim wrote: “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!

“I gained 60lbs during my pregnancy but have been an extra 10 lbs up for the last few years so it’s time to really get to my goal.”

Kim – who is also mother to two-year-old North – added: “This is going to be soooo f**king hard but I can do it and I can’t wait to share it all with you! #BeastMode #WhosWithMe ?!?!?! [sic].”

The Atkins 40 diet typically tells users to eat from all of the food groups, including carbohydrates and fat.

It states: “With the Atkins 40 plan, you can enjoy a full range of food options from every food group – carbohydrates, protein and fats – while still losing weight and feeling satisfied, never hungry! Vegetables, pasta, even potatoes? Yes! You can have it all on the Atkins 40 plan, starting from Day One!”

Kim’s trainer previously told new! magazine: “Knowing Kim, she’ll be [at the gym] as soon as it’s safe. What I’ve seen of Kim over the years, it’s not, ‘Oh, I’ve got to work out’ – it’s as built into her routine as breakfast, shower, lunch and work.”

Gunnar Peterson added: “Kim is just on it – it’s what she does.”