"vanity sizing" for eons, but now less expensive stores such as The Gap and H&M have followed in their footsteps. In simpler terms, manufacturers want people to feel good about the clothing they are buying and so they downsize the actual size. So a size 8 in a Banana Republic store, may actually be a size 10 at Target.
What is a person to do? I say fuck it. Wear what fits your body and don't even look at the size anymore. No one is a "00" it cannot physically exist, and yet you can purchase a size "00" in some stores! This is crazy talk. Don't buy into the madness. Don't get hung up on what size your clothing says it is on the tag, it's just one big lie. For every 10 pounds you drop, go buy something that fits your body. Try on all the sizes, who gives a rats ass what it says on the collar or on the waistband. You're not wearing your clothes inside out. If the label bothers you, take it out. We all know the Feds are far too busy pursuing people who remove tags from mattresses, and no one is going to bust you for taking your scissors to your Ann Taylor dress and cutting out The Lie from the back of the neck!
Size is just a number, and by the looks of it, it's not even a real number. So go buy what fits, feel good in what you are wearing. Maybe you can't afford a whole new wardrobe as you lose weight, but one pair of jeans, or a top, that fits you at the size you are, may be all the encouragement you need to keep on track and not feel discouraged. Let's take back our own vanity and not let the fashion industry tell us how to feel about ourselves!