I know we could do all that, and it would likely be met with some success.
The point is - should we? Why waste all those resources in subtly coercing, conditioning and deceiving responsible, adult people into wanting to have better lives? The situation will self-correct in a few decades all by itself, and there is too many of us on this planet anyway.
I have a colleague at work who is younger than me, almost morbidly obese. He is fully aware of it, he even cracks jokes about it. He is interested in reading all the theory in the world about anatomy, digestion, dieting, excercise, even chemistry, but he is too weak-willed to actually hop on that bike (which he bought last year, yet to my knowledge never used so far), or go for a walk. But he's already finished the new Mass Effect game and is up to speed with all the TV series out there. Every now and then, I suggest that he joins us when we go out on light bike trip, or swimming in nearby lake in summer, but he always makes one excuse or another.
Another colleague of mine is slightly older, and used to be almost as obese as the first one. About a year ago, he decided to start cycling to work, and also do some cycling in his free time. He changed a lot, is much more lean (or rather less "unlean", he still has ways to go), and by his own words, feels much better.
Both of them have made their choice, and are making it over and over again.
That said, I'm all for teaching kids good habits, they do not know any better, and it is our generation's task to impart wisdom (or something we consider wisdom, anyway) to the next one.