You'll also want people to RSVP so you have a head count for the caterer. If, on the other hand, your rehearsal dinner will be fairly low-key or small (think: a party at a restaurant or an intimate gathering at your future in-laws' home) then you don't need to be as official with your invitations.
The exact nutritional value of an orange depends on its variety. According to the U.S. Department of Agriculture, a standard-sized navel orange contains 69 calories, 17.6 grams of carbohydrates and 11.9 grams of sugar.
They come in their own package, making them very portable. A whole orange also takes longer to eat than a glass of juice, and contains 30 fewer calories. Replacing higher calorie snacks like chips and cookies with an orange can save you hundreds of calories a day, and possibly up to 20 pounds a year.