The sizes run a bit differently than traditional denim.
But remember, this is a natural supplement that does not carry the risk of side effects that medications do. The absolute most important thing to look for in a Garcinia Cambogia supplement is the purity of the pill. The higher the HCA(hydroxycitric acid) concentration, the more mileage you are going to get out of the supplement.
All brands will contain some amount of the extract from the actual fruit, but the amount of the active substance can vary a lot. There are plenty of fly-by-night products around(pretty much all of the ones in local stores) that only offer a very subpar purity.