Assuming you're not diabetic, you need carbs after your workout to replenish your glycogen. You need enough high GI carbs to spike your insulin. Most recommend maltodextrin (corn sugar) but anything similar will work (table sugar, watermelon, etc). Most recommendations are between 4-1 to 2-1 carb/protein with the former being for endurance atheletes and the latter being strength atheletes.
See the related thread at http://exrx.net/forum/viewtopic.php?t=3 ... sc&start=0
Kenny recommends 15 grams protein/60 g maltodexetrine. Ironman recommends a max of 75 g carbs post workout.
Here's the bottom line: "It's poor judgement not to ingest some type of beverage that contains carbohydrates after your workout. "
Here's a very interesting debate on the subject on another site (Todd Wilson is very knowledgeable and credible):
http://drsquat.com/forum/viewtopic.php? ... sc&start=0