#1
is it safe to eat protein shake on an empty stomach?? when i drink the one before i sleep, i'm usually hungry by then. so i'm just wondering if its safe
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#2
I dunno dude... i had one of those before when i hadn't eaten in a day or so... and i threw the thing back up within 15 seconds
#4
I just threw a quarter tub full of protein shake powder out. Did nothing for me. Guess I was too young when I was using it. I think you need to be at least 21 for proper effects. ANYWAY

It should be alright for you to have them on an empty stomach. However seems a waste, it won't do much for you that way. For it to have an effect you want to be going to the gym and doing an intense workout, then coming home, eating a good meal and drinking the shake at the end.
#5
Protein shakes are only for if your doing proper muscle building exercise, like a very physical sport or alot of gym work. Also, you've got to be consuming plenty of calories so that your not just using the protein for energy. You only need about 0.7g per lb of bodyweight and thats for serious muscle building. any more than that is just a waste. And people any age can benefit from it, just if your not using it, your literally pissing it away, because its just broken down into urea (part of urine)