American sizes are different than other places. She probably does wear an American size 0. When I'm in Alaska/Colorado where my parents live, I wear between a 00-2 depending on the pants, but when I'm at home in Canada I wear 2-5 depending on the pants. Clothing sizes are such a bad way to measure someones weight/size!
I feel really sad that this happened in Brasil (I am brazilian). I think she is just perfect in Brazil and in any other part of the world... There are way more things to care about than her weight... She is perfect... I wish I had the opportunity to meet her :'/