Alright let me throw you all the mans perspective on sizes, even though I am outnumbered here. Size for me changes with the clothing manufactures and brands. I find this in almost all clothing except for socks and underware. People laugh when I tell them I wear an 18 and a half neck size, at my height 0f 5-6 and weight of 214, in theory I should only have a neck size of 15 maybe 16. Each of us has different builds and this is why you as an individual is different from those of the same height and weight. My upperbody is built like a football player and it is common among the men on my fathers side of the family. So in short I hope maybe my man's perspective pointed you in the right direction of thought. Don't fret over sizes, get to your goal and the rewards is great health and happiness.