Turn off the TV.
Create Rules. It's easy. The household is NOT a democracy. It doesn't matter that there is trash on TV. It doesn't matter that the media markets "bad" foods to kids. Guess what!? YOU are the parent, YOU hold the money, correct!? Why blame other people for the way you are raising your kids? Seriously, people. It's not like my 9-year old daughter is going out buying Snickers for herself, or ice-cream bars, or even Lucky Charms. If she were fat, it'd be MY fault as THE PARENT, not Lucky the Leprachaun's fault.
Actually.....I remember getting food from different places because my mom wouldn't buy it for me. It didnt stop me from eating what I saw on TV.