The teenagers body and the tragedy of unnecessary lack of knowledge.

When I was a teenager noone told me at school or at home what I have read here about the needed weight gain that happens because the body is developing into an adult body. The teenagers should be warned againt dieting in this phase. (I was encouraged to diet by a nurse, and I wasn't even overweight!) If the teenagers knew that the body develops untill they are 25 and that they shouldn't mess with the body and be judgemental about the look of it before they saw the end result in their twenties (and hopefully don't be judgemental about it then either, of course). If they knew the body would look less swollen later if they just waited to see, many wouldn't have started dieting, I think. It could prevent it, at least for some. Why on earth are they not told this and encouraged to trust their bodies? I think it is sad and upsetting.
At least the school nurse could have the task to speak about it for the entire school every year. About the body changes, the importance of respecting their own and others boundaries for intimacy and privacy, warn against commenting and criticising, learn about communication, solving conflicts, expressing emotions and so on. Mental health, is that a taboo subject or are people so materialistic that they don't think it matters (because it isn't matter)?