Saw this Nature of Things program called Microbes: The Hidden Reasons Behind The Obesity Epidemic.
The show focuses on these microbes in the lower intestine that could be linked to our health and obesity. It definitely touches on processed food and why it is unhealthy and briefly on some foods that are believed to be healthy based on helping ensure the microbe environment in our guts stays healthy as well.
I listened to it and found it, like most things based on some common sense, but it went further to try to link why some of things that are good for us are good, and conversely why the bad is bad.