Why exactly is just about every suggestion on combating the obesity problem being treated like it must exist in a vacuum? Seriously, comprehensive plan:
1) Institute a nominal tax on non-necessity food items that are high in sugar (sodas and candy and ice cream and etc). Use the revenues to subsidize healthier food.
2) Institute regulations on how much sugar can be added to "necessity" food items like bread, milk products, crackers, canned fruits and veggies, etc.
3) Bridging points one and two, set a standard for sugar content that heat'n'eat meals that would place some of them under the sugar tax and some not. Microwavable meals aren't strictly a necessity, but they are a definite boon to some families.
4) Institute regulations on what foods are available in school cafeterias.
5) Better nutritional education in schools! Phys ed classes that focus more on exercise than learning a bunch of different games!
6) Go after corn subsidies and sugar tariffs that artificially skew prices on cane sugar and HFCS.
Seriously, there isn't a magic bullet of regulation that will make the problem go bye-bye and personal responsibility does play a role. However, there are steps that can be taken to try and minimize the problem. It's not "tax sweets or end subsidies or better education".