Water! This cannot be stated enough. This will not only keep you hydrated (obviously), it will keep you feeling full and looking fresh all day!
Breakfast - Lots of protein and fruits. Look for good whole grain/ fat combs such as peanut butter or greek yogurt. This combo will keep you energized without feeling bloated. Oatmeal is another great breakfast that will keep you going without the additional calories.
Snacks - Eat all day long! Once your wedding ceremony and pictures begin, you will not be able to eat as much. Again, protein will help keep you going all day long. Also, fruits are great to snack on. Think trail mix, veggies and dip, avocado or peanut butter.
Dinner - Make sure you sit and eat dinner! You should be the first to be served so hurry and eat something while your other guest are getting served. You can also have the caterer put something aside for you to take home with you. You will be so thankful for the late night snack!
Stay way from dinner rolls, red wine, or foods that will show up between your teeth.
Most importantly....eat cake! You've worked so hard to get to this point, now enjoy it!