Weider Premium Whey - shake

I've been looking around but I didn't really got a grip. It's a banana falvour and I was wondering, if I drink it in the morning, within the 30 minutes of waking, when would it be ok to have something to eat? Because i know it causes a insulin spike and I shouldn't put it together with food for a period of time.

And also, could I drink it after gym, considering that I go to the gym in the evening?

I know casein would have been better, but a friend of mine got it for me.

And also, I read on the eslowcarbdiet that whey might limit weight loss, it that true?