Whether you're trying to lose weight, build muscle, or train for a specific sport you need to feed your body the right nutrients, in the right amounts, and at the right time. Your pre-workout meal prepares your body for what’s coming, and what you eat afterward maximizes the work completed while preparing your body for the next session. I always recommend eating an hour before you workout depending on if you get nausecous or not working out on a full stomach. Same goes for your post workout meal, I recommend eating within an hour after you workout.
Like food that expires, your body has a “optimal window” of time to take in carbohydrates and protein after each workout. The longer you wait to refuel, the less amount of time your body puts those nutrients to work. After you workout your body needs those nutrients to recharge and speed up your metabolism. Whether you’re looking to tone up or build muscle, this metabolic window is important no matter what your fitness goals are. Try to consume carbohydrates to refuel and prepare your body for your next workout while consuming protein to help repair and rebuild your muscles as well. For muscle building, taking in post-workout protein is essential. The amino acids in protein are the building blocks of muscle, and growth cannot occur without them.
You can’t work out once in a while and expect to see results, the same goes for your nutrition. Why work your butt off and then not eat or eat like crap after your workout? Your body and mind need to be in a consistant routine to maximize major results. “Feed your muscles what they need after every workout within the metabolic window, and you will be amazed at the body you'll achieve.”
Men’s Fitness. The Truth About Post-Workout Nutrition. By: Tom Holland. http://www.mensfitness.com/nutrition/what-to-eat/truth-about-post-workout-nutrition