You shouldn't listen to those stupid BMI calculators. Haven't you noticed that there are advertisements for diet pills next to all of them? Or "secret" fatburning tips? Yes, there are people who are overweight, but that could also be from a disease, like diabetes. A reason why kids become overweight, is because they are exposed to excessive video-gaming at an early age. I didn't get involved in video games till I was 8. And I still don't play that much. I play football, basketball, baseball, BMX, Snowboard/Skiing, and other stuff. I ain't too worried about being 135 lbs. I weigh more than a kid in my school who is a little on the chubby side, and he's only 130. These BMI thingymabobbers are to scare people into buying diet pills and weight-reduction thingies.
BTW, I think Switzerland has a higher % of "overweight" people. I don't know if this is true.