I'm under the impression you're from Ireland judging by your username. Kids and adolescents that are well fed tend to grow more than those that aren't, and port

I'm under the impression you're from Ireland judging by your username. Kids and adolescents that are well fed tend to grow more than those that aren't, and portion size in the US tends to be substantially greater than elsewhere, especially Europe. Also, there seems to be a greater focus on working out for aesthetic reasons in the US. All of this is, however, does appear to be changing, and moving more toward an American norm. You may also be suffering from confirmation bias! Or, you're right and something in American food is affecting growth rates, but there doesn't appear to be a lot of evidence to support this notion.