Let's apply some of our knowledge and skill with a real example.
  1. According to the (not perfect) Dietary Guidelines for Americans, there are certain things to avoid and others to include to improve overall diet.
  2. The better way to use the % categories on a food label is to consider whether that particular item is low or high.  If an item, say sodium, provides 5% or less of the daily value - then it is low.  IF it contains 20% or more it is high,
  3. The items that we want to be low are, sodium, saturated fat, cholesterol, trans fat, calories and sugar.  (Calories and sugar do not have a DV - but consider less than 5 or 6 grams per serving or 100 calories, and 200 or less calories, to be low).
  4. The items we want to be high are potassium, whole grains, healthy oils, fruits and vegetables, vitamin D and many would say, calcium.  The Nutrition Facts Panel lists fiber, not whole grains, but you can use that instead.  
  5. Every food does not contain all the items.  Another thing to review is the ingredients list.
Okay.  Pizza time. Starting with the nutrition label,  I have circled in red the things we should limit (5% or less) and in green (20% or more) the things to get more of.  There is of course a middle category - you can figure that out yourselves.

I am not sure how big the pizza is but it is to be cut into five pieces and each one has 270 calories - it weighs 131g so it is over 2 cals per gram - this is a pretty calorically dense food.  Remember that low energy dense foods have less than 1 calorie per gram.
There are 10 grams of sugar in a slice, which I consider high for pizza.  It is high by serving size but not the 5 grams per 100 calories criteria.  Well - as you can see below, the cholesterol is low, the potassium is too - but it should  be high.  Calcium looks good, sat fat does not.  Sodium is high and it should be low.

The ingredient list is at the bottom.  Sorry I couldn't adjust this layout better.  I find it interesting that salt and sugar are mentioned multiple times.  Also - the number of items that are hard to pronounce should get your attention.  The list doesn't look too bad.  Skim milk cheeses are used, but there may be a lot of preservatives.  Olive oil is a healthy oil and that is on the list which may explain why only 3.5 grams of the 11grams of fat are saturated.  There are no whole grains that I could identify.

SO- I hope you had fun and that you will give your next food label the attention it deserves!