I never understand why people forget that women's dress sizes are based on circumference measurements of hips, waist and bust.
Size 12 might mean a petite woman(should be a size 8 say) with a lot of fat making her up to a 12 or might mean a tall woman with wide hips but normal bodyfat levels being a size 12. If this normally size 12 woman was fat she'd maybe be a 16.
They would be better to concern themselves with waist to hip ratio or simply how they look in a mirror.
With men for example, a naturally broad shouldered man might never be able to fit into a large shirt no matter what his fat levels due to the distance around his shoulders(bone structure/frame size). Maybe his natural size is XL. Accept it.
On the other hand a fat man who normally wears an XL shirt, trains, diets and now fits into his normal size which for him is a large as his frame size does not require an XL shirt.
Does anyone get what I'm saying?
Women trying to shrink to a size that only petite women can do is like a middleweight boxer trying to make the weight for a flyweight fight. Different builds, not possible.