Kim Kardashian is back in a bikini, six months after giving birth to daughter North West. The reality-TV star shows off her new curves on the cover of Us Weekly.

A source tells the publication about her weight loss: “Kim feels confident again. She worked really hard and is so motivated to stay fit.” To start every day, Kardashian reportedly has been doing 100 squats, which would explain her infamous derriere.

In the cover photo, Kardashian is on the beach in a teeny white bikini, and the caption reads, “My Body Is Back! No Gimmicks, No Surgery!

In November, the 5-foot-3-inch beauty credited her weight loss to the Atkins diet, a low-carbohydrate meal plan. Carbs are drastically reduced, and dieters consume more protein and fat than they would on a standard diet. The body then uses fat as fuel, causing rapid weight loss.

“What distinguishes the Atkins diet is the absence of a lot of carbohydrates, so that leaves out a lot of choices,” Jonny Bowden, author of "The Great Cholesterol Myth,” told E! News recently. “You can make bad choices and good choices, but there's nothing dangerous about the Atkins diet. There really isn't a downside to it." 

During a recent appearance on "The Tonight Show With Jay Leno," Kardashian admitted that getting rid of the extra pounds after the birth of her daughter was the “greatest challenge” of her life.