As long as FDA passes food production on unhealthy products, this won't stand. And you can't effectively fine those who can't afford food to begin with. The knowledge generation gap is too big to believe current young adults even know how to be healthy, or raise a healthy child. Schools will have to reemphasize and mandate increased activity to promote health. This will result in kids complaining, parents taking their side, and a doctors note limiting the child's ability to exercise supported by false asthma symptoms or the like.
Taxing fat will never work.
Give tax breaks for current medical check ups showing you are healthy. Then, obesity may have a motivator. But then again, why should people be given benefits for what they should be doing anyways?