I thought it was pretty common to know about calorie counting at that age? Maybe not "diet/gym culture", but I always tend to tone down the content of these stories since they tend to be over exaggerated quite a bit.

I mean I remember learning about how to read nutritional labels and calculating recommended calories in middle school.

I don't really think I'm disagreeing with you though. On top of the possibility of encouraging eating disorders I think it also encourages overweight kids to stay overweight. I was morbidly obese (200 pounds) at age nine and introduced to the concept of calorie counting and monitoring exercise. I think if it hadn't been made into some huge, big, complicated, situation, that had cold hard numbers telling me I was a failure I wouldn't have shoved in into the back of my mind as some big "adult problem" I didn't want to deal with.

It wasn't until I actually became an adult and started looking at it like "eat less of what you're already eating and move more than you're already moving" that it started to seem like something I could actually do.