Kristin Cavallari, is looking sexy despite being pregnant with her third baby she does this by eating like a caveman to stay fit as well as working out regularly.

On July 21, Kristin posted on Instagram a photo of herself while lifting weights whilst showing her growing belly. But in the image you will notice how slim and healthy she looks.

Just like any celebrities who eat like a caveman to stay fit, Kristin is a fan of such diet.

"I'm a freak about what I put in my mouth," said Cavallari. "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."

She also revealed that she only sticks within the parameter of the Paleo approved food.

"I also love avocados with olive oil and sea salt and I put coconut oil in or on everything."

Aside from eating healthy food, she also maintains her workout routine to maintain her toned body. She incorporates her healthy eating with 30 to 45 minutes of workout which is four to five days a week.

Last year, after giving birth to her second child, fans were astonished when she looks so skinny just months after she gave birth.

Cavallari credits her 20 pound weight loss to Paleo style diet and Pilates workouts. She revealed that she stick to the Paleo style to stay fit and healthy, "We eat a ton of veggies, chicken, grass-fed beef, bison and fish," she told Celebrity Health.

Just like Kristin Jessica Biel is also a fan of paleo diet.

The Hollywood actress affirmed that one of her secrets to stay fit and healthy is she included Paleo diet in her regimen.