Okay, fine, several notes to those geniuses. First, obesity is a problem with children in teens, but so are anorexia and bulimia. (It is a problem for young men, too.) While a letter home to parents stating that a child is obese may or may not make that child healthy, these letters and this screening could very well trigger eating disorders in young women and men. Functionally, you are turning these fragile teens into guinea pigs in a social engineering experiment, attempting to find out whether or not quantifying a student’s ‘obesity’ is going to do more good than harm.
Second, BMI is a miserably terrible way to measure obesity. It’s epically flawed. A muscular person can be ‘obese’ and have nary an extra ounce of fat; an unhealthy couch potato can be a ‘normal’ weight, due to having a small frame but lots of extra weight. Muscle weighs more than fat, which is why people (especially teenagers) can gain weight when they get in shape, although they may drop a dress size. (Back when I was 19 or 20, a nurse at my doctor’s office weighed me; I was just under 130 lbs, and I’m 5’8. She then told me that I should try to maintain that weight for the rest of my life. Yeah, that’s a healthy, realistic goal for a middle-aged woman – try to maintain her college athlete weight.)
In fact, BMI is so absurd that it makes no distinction between men and women – it assumes that a healthy weight for a man is a healthy weight for a woman, and vice versa.
Finally, let us remember that this entire exercise is predicated on the notion that a parent cannot tell when his or her own child is not a healthy weight. These parents have nurtured their children since birth, fed them every day, buy their clothes, see them every day, talk to them, know what sports they are playing (or not), and know how much time they spend in front of the TV. Yet our government thinks that they need to tell parents when their children are not a healthy weight? Japan and China are kicking our collective scholastic arses, and school systems are now spending their limited resources telling parents that their kids are fat? Rather, no wonder why Japan and China are kicking our academic arses: we’re spending our time telling athletes that they are fat, couch potatoes that they are skinny, and getting everyone into sex ed, and they are teaching calculus.