You have been working out, and that means your muscles used metabolic fuels quickly. Moreover, to allow you to workout for a good period of 45 minutes or longer, the body had to mobilize its stored fuels to make fatty acids, glucose, and amino acids available for oxidation.
This is called the catabolic (growth) process and cannot occur simultaneous to anabolic (repair) processes such as glycogen formation and protein synthesis. We need a post-workout meal.
High Protein Diet
Therefore, after a workout, your body must switch over from a catabolic environment to an anabolic one. The post-workout meal will effect your hormonal environment so this can take place. A good post-workout meal will provide carbohydrates, proteins, and fats into the body so it can begin repairing damaged tissue and rebuilding up your fuel reserves.
Proteins
Proteins are crucial to post exercise anabolism (repair). Why? Because Protein will provide essential amino acids needed to rebuild damaged tissues. In fact, the body itself needs somehow to adapt to the workout rigors, and protein gives it those essential amino acids required for endogenous protein synthesis. In other words, the body's ability to adapt to exercise is dependent on getting available protein.
How much protein is required after a workout? No one is exactly sure. Right now, professional trainers think the total protein intake for athletes is between 1.6-1.8 grams per kilogram body weight. However, you must know your body can't effectively store amino acids. So, you must in any case, eat proteins every 3-4 hours.
A post-workout meal should contain some slowly digesting protein that will allow a steady release of amino acids into your system well after your workout.
Carbs
Even as carbs are important for endurance in your workout they are crucial for glycogen recovery. Today there is a great deal of discussion on what type of carb is best for post exercise recovery.
There is the commercial point of view that wishes you to drink an expensive sugary solution with other additives. Some trainers advise a simple sugar and water solution, and other advice eating a good meal.
The truth is that no matter what you eat, the results are about the same, as long as there are sufficient levels of carbs present. This is true whether or not the carbs are alone or with other nutrients. You need to replenish your glycogen and you do that with carbs.
Fat
There is also an on-going argument about if fat should be added to the post-workout meal. One point that is agreed upon is the fats should be in the form of fatty acids such as Omega-3 and 6.
Liquids.
It cannot be stressed enough that you need to replenish your liquids after a workout. A general rule to follow is about a 3 glasses of clean water over an hour after the workout session
An Ideal Post-Workout Meal
A simple sandwich is perfect. The bread should be high quality whole wheat or rye, and the contents can be tuna or bacon and tomato. No mayonnaise should be used, instead use high quality extra-virgin olive oil. This meal or similar will give you all you need for that post-workout recovery. If you are prone to the pre-mixed drinks available, compare the labels and prices, and make sure there are enough carbs and proteins (and not too much) for your constitution. Your body will know when you have had too much.