Kristin Cavallari welcomed her second child, Jaxon Wyatt Cutler, into the world this past May and she already has her fit, toned physique back. So how did the reality TV star get back into shape barely 12 weeks after giving birth?

Kristin Cavallri
Cavallari has got her fit, toned physique back three months after giving birth

Even though Cavallari may be genetically gifted, the 27 year-old realises that there is no easy way to shed those pounds, and it is all down to a healthy diet, lots of exercise and breast-feeding.

"I'm a freak about what I put in my mouth," the mother of two told E! News on Friday (Aug 1st). "I'm constantly reading labels and I don't eat any toxic chemicals, so I think that plays a huge role. I'm breast-feeding, which burns a ton of calories, and I can probably just thank my mama too, you know."

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Cavallari and her husband, Jay Cutler, who married in June 2013, are also parents to a 1 year-old son, Camden, and it seems he isn't warming up to the newest addition of the family.

"He's been great, up until the last two days," Kristin explained. "Yesterday I was feeding Jaxon and he threw a sippy cup at his head and started to kick him, so we're sort of in that phase right now."

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One reason Cavallari may be able to bounce back into shape easier than most is the fact that both of her pregnancies haven't been that strenuous on her body.

"I'm lucky," Cavallari said late last year. "Both pregnancies have been really easy for me, I've just been really tired. It's just one of those things where I could literally sleep all day everyday but I'm snapping out of it a little bit now that I'm in the second trimester." Lucky woman!