Overfeeding? How do you know?

I know bps can eat a pretty good sized rat, but I don't have rats. I breed mice, and so I give him several at one time. (We call them potato chips... you can't have just one!:D) How much should he be eating? Can he over stuff himself? What are the dangers of overfeeding?

Take the body weight and multiply by 10-15% (you can push up to 20%).

Over feeding leads to a fat snake, which would cause the same health problems it does in any other animal.

If they over stuff themselves they will regurgitate the prey, which does a number on the snakes inner workings.

And when do snakes reach their full growth? I mean, at 14yo my guy isn't going to suddenly put on a growth spurt for being fed more than usual?

Sorry for all these questions, but what would be considered a healthy weight for a 4 foot male?