Whether you are going to be doing a cardio workout or a resistance workout, you should try to make it a point to eat a mix of carbohydrates and protein. What determines the percentage of carbohydrates and protein you should consume is whether you are doing cardio or resistance and the intensity level you will be working at.
The ideal time to eat your pre workout meal is 1 hour before you start. If you are working at a lower intensity level, keep this meal down to around 200 calories or so. If you are working at a higher intensity level, you may need this meal to be as high as 400 to 500 calories.
If you are doing a cardio session, you will need to eat a mix of around 2/3 carbohydrates and 1/3 protein. This will give you longer sustained energy from the extra carbs with enough protein to keep muscle from breaking down during your workout.
If you are doing a resistance session, you should eat a mix of around 1/3 carbohydrates and 2/3 protein. This will give you enough energy from the carbs to perform each set you do and the extra protein will help keep muscle breakdown to a minimum during your workout. It has been shown that your body most effectively uses protein during exertion meaning that taking in more protein before resistance workouts aids in faster recovery as well.
Now, eating after a workout is just as important as the pre workout meal. Remember that when you exercise whether it is a cardio or a resistance session, you deplete energy in the form of glycogen. Our brain and central nervous system relies on glycogen as their main source of fuel so if we don't replace it after exercise, our bodies will begin to break down muscle tissue into amino acids, then convert them into usable fuel for the brain and central nervous system.
Also, mostly during resistance workouts, you break down muscle tissue by creating micro tears. This means that right after a workout; your muscles go into a repair mode. Proteins are the key macronutrient for muscle repair and so you don't want muscle breaking down further to create fuel in place of lost glycogen.
If you have just finished a cardio session, you will need to consume mostly carbohydrates, preferably ones with high fiber. Oatmeal, rice, whole wheat pasta, and most northern fruits are good sources. Try to consume around 30 to 50 grams of these carbohydrates after a cardio session. After cardio, it is ok to eat within 5 to 10 minutes of completion.
If you have just finished a resistance session, you will need a combination of carbohydrates and protein. Because unlike cardio workouts, with resistance workouts you are breaking down muscle tissue by creating micro tears. The protein is needed to build up and repair these tears so the muscle can increase in size and strength. The carbs not only replace the lost muscle glycogen, but also help the protein get into our muscle cells so it can synthesize into structural protein, or muscle itself.
Chicken or fish with a potato, egg whites with a piece of fruit, or a protein shake with fruit mixed in are good meals after resistance workouts but remember to keep the fiber low here. High fiber slows down digestion, meaning the protein will take longer to reach the muscle cells.
After resistance, it is recommended to wait 30 minutes before eating so as not to take blood away from your muscles too soon. The blood in your muscles helps with the repair process by removing metabolic waste products from them.
Any fats should be consumed well before and well after exercise.
