Two things that I think are unlikely to be effective: increased parental involvement and school coursework. Both of these solutions imply that parents and teachers are less prone to the problem of obesity than children. In reality, these measures would be like learning math from people who can't do math themselves. Every adult knows that healthy food and exercise are the basis of a healthy life, and everyone knows a carrot's healthier than a Big Mac; to suggest adults (and even adolescents) don't know that would be patronizing. Obesity, then, indicates a general suspension of judgment on adults' parts, and to that end government action to (softly) coerce healthier lifestyles is probably most appropriate.