Hi, usually when you eat depends on what kind of exercise you are doing and when it is done. I usually try to get my cardio in the morning on an empty stomach. Your body, after sleep, is pretty much in a catabolic stage, prime for losing fat. This is WHEN you want to lose weight. Some might argue that if you are trying to put on muscle, then anything more than 30 minutes of cardio in the morning would be counter-intuitive to that. Some even take BCAAs(Branched Chain Amino Acids) to help with that.
To me, and many others, the most important thing after working out, whether it be the gym or doing some cardio, is to replenish your empty "fuel" stores in your body. High levels of protein and mid level carbs are a great way to do that. This helps with that "burn out" feeling some experience after working out. By replenishing your fuel stores in your body, you are allowing your body to keep working at its maximum efficiency throughout the day, AND, helping your metabolism to keep rolling and burning fat.
Hope this helps