The simultaneous gains in obesity and hunger share a common root: The competing interests of corporations and people are represented unequally in the food environment. In the post-Citizen's United world, we might say that the interests of people people are secondary to those of corporation people. This is especially true when the people people are international and don't recognize that the decisions made by the US Congress affect the availability and price of food in their countries.
One example of this is the increasing use of grain to for biofuels. As noted in Eat Drink Vote, "... US farmers responded to congressional incentives by planting corn and soybeans for biofuels. Economists consider this use of food crops for fuel to be the single most important reason for the recent sharp rise in worldwide food prices and worldwide hunger. Millions of people suddenly could not afford to buy the food they need."
Vote with your time: If this interest you, here is a group you may want to check-out.
And here is a list of other groups working on this issue and others.