Yes, you should eat after the gym! We will call this “recovery nutrition”. This is the most important meal of the day by far. It may seem confusing to most, but it is really very simple once you understand how the body works. The number one thing you need to understand is that after working out, you want your muscles to recover. Recovering requires you to replenish muscle glycogen. To keep it simple, muscle glycogen is basically carbohydrates that have been stored in the body to use for fuel.
After working out your muscles become more receptive to producing new glycogen. This usually lasts a few hours. During this time muscle cells will “eat” up glucose as if it were it’s last meal because blood flow to the muscles is much greater. Another thing that happens at this time is muscle cells become more sensitive to the effects of insulin. Insulin promotes glycogen synthesis.
What does this all mean? Basically that you should take in carbohydrates after your workout. As to what type of carbohydrate you should take in, many say it should be something that is fast digesting. Personally my take on this, from my experience, and from what I have read, it doesn’t matter whether the carb is low or high gi (slow or fast digesting). It’s definitely the best time to eat something faster digesting (such as sugary foods) but as a whole it’s not going to matter too much. This means that you can eat whatever type of carb you want after the gym. I don’t mean go gorge on bad food! Make sure the carb source you are eating is low in fat and has at least some nutritional value. Carbohydrates are not the devil like most people are led to believe, the carbs ingested post-workout will be used to restore muscle glycogen. Not eating after the gym may make your body look towards muscle tissue for energy, which would promote muscle loss. Not something you want to promote after working out, right? As far as what type of protein to take in post-workout, I would opt for whey protein. Whey protein is fast digesting which is beneficial, but as with carbs, I believe any source of protein is fine (whey, egg whites, lean beef, chicken, tuna, etc). I would personally stay away from a meal high in fat at this time as it does slow down digestion a bit.
As far as what you should eat post-workout. In a mass building phase, I suggest around .3-.5 grams of carbohydrates per pound of body weight and .25-.4 grams of protein per pound of body weight. This would mean that if you are 200 pounds you would intake roughly 60-100 grams of carbohydrates (240-400 calories) and 50-80 grams of protein (200-320 calories) post work-out. In a cutting phase, I suggest .2-.4 grams of carbohydrates per pound of body weight and .2-.3 grams of protein per pound of body weight. Again, this would mean that if you are 200 pounds you would intake roughly 40-80 grams of carbohydrates (160-320 calories) and 40-60 grams of protein (160-240 calories) post work-out. I would stick more to the middle end of these numbers, and for women the lower end. Protein is the key to building muscle after exercises; carbohydrates are more about refueling. I suggest eating or at least having a shake with-in 60 minutes after working out. The meal should be based off your carb/protein needs and low in fat. After this meal has been eaten, move on to your next scheduled “normal” meal for the day. I usually wait 1-2 hours between my post-workout meal and post post-workout meal. As I said before, this may not suit your individual needs. Depending on the type of diet you’re on, intensity, etc, you may want to lower or raise the intake.
This is just my take on post-workout eating. There are countless “studies” that say one thing and then 50 others that say another thing. The thing everyone needs to do is try different stuff out and see what works best for you and your body. This is a base I have always gone by, what has worked for me, and what I suggest my clients do.
You must always keep yourself hydrated as water is just as important. Keep drinking water even after you exercise!