The ones I've had in the shelter WILL get bloated and diarrhea, and vomit if I overfeed.
I try to give them about half of what I would normally. As their body adjusts to being fed again, I increase their food. They can tolerate a regular diet after a week or two.
It really doesn't take alot of time at all for them to regain weight that way. I've had my cruelty case (starvation and other things) since October and had to cut his food back because he was getting too FAT!
The only true wisdom is in knowing you know nothing.