You know what i think it is....I am definetely smaller size wise at this weight after doing low carb than on other diets or even when I was just thinner naturally.
I was wearing a 10 after weight watchers at a similar weight to what i am now. After low carbing i consitently wear a 8 and some 6's...

I think low carb helps you maintain lean muscle and lose more fat. that is why clothes fit better now than they did at the same weight previosly in our life.