The reasons for avoiding "ultra-processed" foods are spelled out here:
Ultra-processed foods, he says, are the primary cause of the rapid rise in obesity and associated diseases throughout the world.
He charges the food industry with creating durable, convenient, attractive, ready-to-eat or ready-to-heat products that are so palatable that they are habit-forming. And they are meant to be eaten everywhere - in fast-food places, on the street and while watching television, working or driving.
Ultra-processed foods are much higher in calories for their nutrients than unprocessed and minimally processed foods. They have loads of fat, sugars and salt, but are low in vitamins, minerals and fiber.
Read more: http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2010/12/03/FDTR1GJ2PS.DTL#ixzz17Kt4Wwnp
As I've stated repeatedly, if you're really, really serious about taking off weight and keeping it off, the number one thing you should do is just say "NO" to ultra processed foods.
I'm not saying it's easy. I'm not even advocating that you go "cold turkey" when it comes to banishing sweetened canned or bottled drinks, Doritos, Ho-Hos and convenience dinners from your diet.
Instead, I think the best route is to gradually replace the "junk" in your diet with what Michael Pollan calls "real food."
Instead of that 100 calorie pack of Chips Ahoy for a snack, have an apple, some grapes or even a handful of nuts and raisins.
Instead of reaching into the freezer for dinner, make a simple dinner of pasta with some fresh sauteed vegetables.
Make the changes gradually, and over time move to eliminate more and more ultra processed foods from your diet.
Add a little exercise, and the weight will just fall off.
I promise it.