Taking in nutrients directly after a workout is imperative. It aides the body in recovery, repairs muscle cells, reduces soreness, raises hormone levels, and refills glycogen stores. The sooner nutrients are consumed and absorbed, the faster the body goes from a catabolic state (muscle destroying) to an anabolic state (muscle building) This is why a liquid meal is better post-workout than a solid meal. A liquid is more readily absorbed by the body than solid. This isn’t to say a solid post-workout meal is bad. Liquid is just slightly better.
What do you consume after a workout?
First off you want a carbohydrate high on the glycemic index (GI scale). Eat a high GI food when your glycogen levels are full is a bad idea, as your body will store the excess as fat. However, when your body is depleted of glycogen (after a workout), a high GI food is the right idea. Insulin is released after consumption of high GI food. Insulin is a protein hormone that is vital for metabolism of carbs, fats, and proteins. Having an elevated insulin level slows down the decrease in amino acids and keeps a positive nitrogen level. To complete the process however, you need to introduce protein to the equation. A fast digesting protein, such as whey isolate (protein powder) combined with a high GI carb will result in significant muscle growth. Aim for a ratio of 2.5 carbs:1 protein.
There are other things to consider, but for practical purposes, this is a great routine to get into following your workout.