When I started Atkins I lost weight quickly - so fast that I deliberately slowed it down - rapid weightloss is not good for you, it is not a success to be dropping weight - having seen people who achieved their teenage weight with their latest diet and looking as though they have aged ten years in the process it is not something desirable.
Personally I find that if I eat low carb foods, 10 percent carbs or less, and less of them in the mornings, my BG and energy levels are good. I don't really need to think about portion size for those foods, though peas and beans of all kinds I do, I seem to be sensitive to them, and anything higher than 10 percent I really need to restrict the amounts I eat.
I have never been able to prove that calories in the diet are what controls weight - on a low calorie diet I just collapse, white faced and fainting, and do not lose weight, but on low carb I have no calorie restrictions and I am now 15 percent lighter than when on the 'cholesterol reducing' diet pre diagnosis, and without even trying.