No, what would be effective is if the parents of children stopped letting 'em eat junk food all the fricking time. "Mummy, I want a Snickers". Bad fricking luck, kid, eat your fricking vegetables.
It's somebody else's issue, and I refuse to accept any responsibility or worry over the fact that somebody else's kids are fat. I have enough problems of my own, I've got better things to do than accept part-ownership of the easily-soluble problems of others.