Alan, I spend a lot of time in China. Obesity was almost unknown there until the last few years, but now it is becoming a significant problem with certain sectors of big city adolescents, and it is simply because they are getting hooked on Fast food rather than Chinese food - notably Pizza Hut, KFC and McDonalds. I accept your point about freedom of choice, but not everybody is as well-informed on the subject as you probably are. Personally, I think I've eaten in McDonalds 2 or 3 times in my life, and on the last occasion came down with Salmonella poisoning next day, and turned vegetarian.
You have to admit the processed and fast food industries in general target kids in very sophisticated and , in my opinion, immoral ways, and that can make a mockery of the concept of freedom of choice