Replacing muscle glycogen stores following your endurance run is a great deal. Restoring your glycogen stores minimizes chronic muscle fatigue and aids in a quicker recovery.
While most people are not hungry after an endurance exercise it's vitally important to at least drink a high carbohydrate drink. I've even actually read the higher the Glycemic Index of a food post recovery the quicker and easier it is for your muscles to recover. Right, think about it, it does make the most sense. You provide your body with simple sugars to replace the glycogen. There is nothing complex about simple starches (like potato's!!) after a big run to quickly get these sugars into your body so they can be stored in the muscle. complex carbs take longer to break down and therefore take longer to get into the muscle for recovery. So aim for refined carbs 'afer' the work-out in contrast to complex carbs 'before' endurance runs!
So how much?
Within the first 30 minutes of exercise you want to have your first attempt at carb recovery with 1.5grams per kilogram your body weight. Then 2 hrs later eat a solid meal with 1.5 grams per kilogram of carbs and toss in some protein at this point too.
Oh let me be American For you and cover that Kilogram to your lbs.
So example: 154lbs=70 kilograms therefore I should consume 70x1.5=105grams of carbs within the first half hour of the run and then again 2 hrs later!!
So most my Running Crew loves chocolate milk for recovery (getting electrolytes, simple sugars!) and that has about 26g of carbs per 8oz drink. So drink 32oz of chocolate milk and you have started the process of carb recovery and you promoted re-hydration!