Kim Kardashian's Nutritionist Reveals How She's Already Dropped a Whopping 42 Pounds!

toofab's Brittany Kyles chatted with Kim's nutritionist, Colette Heimowitz -- who's also the VP of Nutrition and Education at Atkins -- where she revealed what it's been like working with reality star and how the mother-of-two has bounced back so quickly after both of her pregnancies.

"Well, you know, she gained 60lbs with her second pregnancy again [laughs] and she wanted to get back to her pre-pregnancy weight," Colette tells us about the "Keeping Up with the Kardashians" star. "She succeeded with Atkins with her first pregnancy and she remembered from doing it in college with her dad [Robert Kardashian], so family was there and it was familiar to her and she succeeded."

"She was able to reach her weight loss goals and keep her energy up, preserve lean tissue, you know, have her appetite under control," she continues. "She's great to work with because she is committed and very motivated which is a pleasure. As a nutritionist, you're only as good as you patient is compliant. So working with her has been a real pleasure."

Kim proudly revealed on her app on Monday that she's already down 42 pounds since welcoming her son Saint West in December and has just 28 pounds more to go.

While Kim's nutritionist says the reality star is rarely hungry on Atkins, sugar has definitely been one of the harder ingredients for her to give up.

"Well we're all sugar babies, we love sweet things, and those are usually high in sugar and high in carbohydrates," she says. "The success on Atkins is getting carbohydrates low enough so that the body burns fat as its primary fuel source. So you burn the fat you have stored and you burn the fat you are eating."

"So right now Kim is eating a wide variety of foods that include proteins like fish, chicken, eggs or different kinds of meat, colorful vegetables that are high in fiber, low glycemic fruits that are high in fiber, healthy fats like nuts and avocado," she explains. "The combination of high fiber, optimal protein and healthy fats really control the appetite."

Though sugar tends to be the hardest to give up, Colette says it's the number one food/ingredient to avoid when you're trying to lose weight.

"Stay away from juice, stay away from bagels -- they're like 60 grams of carbohydrates and then you are hungry two hours later -- stay away from a lot of bread and read ingredients," she says.

Colette also says successful weight loss has to do with to the way you think about food.

"Rather than thinking 'I can't have,' you wind up being more successful knowing what you can have," she explains. "No amount of will power is going to keep you from having a doughnut if you are hungry. So it's more important to stay fortified. Don't skip a meal, make sure you have snacks in your bag if the meal is delayed, have protein at every meal, when you choose a carbohydrate choose a high fiber carbohydrate (like fruits, vegetables, nuts) or a little brown rice instead of white rice."

Clearly Colette knows what she's talking about -- Kim's looking pretty darn amazing these days!

"We're really excited for her," Colette says about Mrs. Kanye West's success.