It is extremely important that you eat something after a run, especially a very long one. Because running takes a lot out of you, you must replenish your energy post-run. According to Christine Luff, author at About.com, a good reason to hit the kitchen or cupboard after running is that “you can minimize muscle stiffness and soreness,” if you eat within 30 minutes of the run.
Think of post-run (or post-exercising for that fact) snacking as a way to ‘fuel your fitness.’ You need to energize the body so it can work to it’s maximum potential to create results.
You will want to make sure that your snacks are full of carbs and some protein. If you have ever signed up for a race, you will notice almost always they have a huge selection of foods after you cross the finish line. Often bagels, bananas, other fruits and sometimes a bbq.