For what it's worth, I tend not to eat a lot of carbs but am not on a diet.  For whatever reason I have just never been a huge fan of bread and potatoes and such.  I tend to eat a lot of Asian food and I also tend to go for wraps rather than regular sandwiches.  I also tend to eat a lot of green things and not a lot of sweet things.  I probably also am a bit more active than most people - I walk a LOT.  I've been pretty stable at 145 lbs and a 28 in waist since high school.