An adult male does not need much more than a small/small rat every seven days (40-50 grams). All my adults get one that size every week. For me, that's about a 4-5 week old rat.
Think that's not enough? Take a look at this:
http://www.ball-pythons.net/forums/s...8&postcount=15
Here are a few discussions on the same topic:
http://www.ball-pythons.net/forums/s...highlight=rats
http://www.ball-pythons.net/forums/s...ht=small+small
http://www.ball-pythons.net/forums/s...ht=small+small