BMI is a useful tool when pulling statistics for a million people. It is useful in studies like these. For an individual, obesity can be easily seen. Bodybuilders are heavy not obese. But I doubt many of the severely obese teens were bodybuilders!
Find it very hard to believe the bmi is even accurate in general. I recall reading once (years ago, unrelated to covid 19) of a study of residence at a retirement home that looked at their bmi vs how long they lived. Don’t recall details but do distinctly remember that the weight range that lived longest was overweight according to the bmi charts.
My daughter’s boyfriend works out every day with barbells and such. We have seen him go from a trim athletic build, to very round. It shows in his face, his abdomen, and to a degree, all over his body. He may think he’s healthy, and yes, he is more so than someone who isn’t working out, but I guarantee you that he is more than overweight now. He told us he was allowed to get his vaccine early because “technically” he’s obese. When I look at him, I don’t see an athlete. I see a mildly obese person who doesn’t try to control his food intake. He thinks that because he’s young (34) he is still healthy with a round figure. I want to caution him about his weight, but I know I would risk damaging my relationship with my daughter if I did that. For both of their sakes, I’d like him to lose a few pounds.