Processed foods have little nutrition and contain ingredients not found in the natural world. Even foods that are considered healthy because they are low fat or low calorie have little to offer you. Like pretzels. Pretzels might not add a lot of calories to your diet, but they also don't add a lot of nutrients. Challenge yourself to cut out all processed foods for a week. It will most likely require some planning on your part, but I guarantee that you will feel the difference after a week.