My DH and I eat according to the primal / paleo diet. Basically only natural food that can be eaten without processing. Lots of fruits, veg, meat, and nuts. A bit of dairy. No processed food - grains, beans, sugars. I allow myself to cheat occasionally but since I can still eat bacon, butter, eggs, fruits, etc there is a lot of good stuff in there. And large portions of the allowable foods are allowed, and there is also an exercise program... Basically lots of movement with spurts of cardio and heavy lifting (like a 'caveman' would do) :-)
Tons of info and recipes online. It's not the same as Atkins. In my last pregnancy I only gained 20 lbs and had a very healthy pregnancy, and lost it all in a month.
I would recommend looking into it!