Read this

Salt Sugar Fat by Michael Moss

http://www.npr.org/blogs/thesalt/2013/02/26/172969363/how-the-food-industry-manipulates-taste-buds-with-salt-sugar-fat

This book examines the history of the food industy and reveals current practices from some of the food giants-such as Kraft and Nestle and how they have engineered their products to be the perfect blend of salty, sweet and/or fat. 
The amount of money and research that goes into food engineering is just mind blowing and it makes them millions and millions of dollars a year.
Definitely eye-opening and worth the read. 

Particularly insidious is how some of the food companies actively tried to challenge and put out of business home ec teachers and departments. Enter the rise of Betty Crocker as the perfect blend of modern convenience and happy homemaker, specifically marketed to get consumers out of the kitchen and away from making things from scratch.

After all the research though, the conclusion of the book comes down to 1 thing- personal choice.  Be armed with the knowledge of what's on the shelves at the grocery store then make the right choice about what you put into your body.