Thats right... it should ALWAYS be after a workout NEVER before, atc least thats what my step brother says and he's a trainer at Golds gym and my hubby asked him the same question . Your body needs it after to rejuvenate.
Most people working out don't take it to gain weight.They take it after a workout to rejuvenate and repair which is what is needed. Your body needs protein after a strenuous workout. If you are only taking it to gain weight, you would be drinking more than one before a workout during the day.You would probably have to drink it whenever you want to. I was talking about repairing your muscles. I have asked 2 people again since then and they both work at golds gym, my bro and his girlfriend both trainers and both have trained my husband and they both said AFTER a workout if you want the benefits of it.
The Right Answer: If you're trying to maximize muscle growth, (which you are if you are lifting), then you should consume your protein shake within an hour of working out. If you really want to maximize your gains, drink a glass of fruit juice along with it. Or just drink a meal replacement after your workout. There's about a 30-20min window after an intense workout where your body is primed to absorb the protein, and it needs to replenish it's muscle glycogen stores, (hence the fruit juice).
It would be smart to drink at least two protein shakes per day.