From what I've been reading recently, the amount of yeast they give you is barely (not) enough anyway. I only ever do 500 g of "sugar" and always use the whole packet of yeast. There is mathematics involved but I doubt you're in any bother from using all the yeast. My father used to do just the can with no additional sugars or malts.
I may not be the best person to take advice from and I hope someone with better understanding comes in here.
Hi Thanks for the comments, main reason of asking is,for the last 2 weeks i've had to drink commercial beer as been away from home, and have notice that my shits are more solid,, wondering if the left over yeast is been drunk and then causing the running shits?