My adults (ranging from 1000-3000g) get 60-80g rats (one) every 6-7 days. The only time I feed 125g+ rats is for the first few weeks after the females lay eggs, since their weight loss is so dramatic then. I apply the 15% "rule" to younger/smaller snakes. I have a few girls who would take the larger size if offered, but like Rich said, then I just get more poop! Those are the females that get an occasional second helping if someone else doesn't eat.