A lot of people say this is related to colic/gas due to foremilk/hindmilk imbalance. However, i've had two doctors (one of whom is recognized as a bf expert) tell me that that is outdated info (although they never told me what research their "new" info is based on and I keep forgetting to ask). My family dr said that my ods's green poop was due to a fast metabolism - everytime he ate he pooped - and b/c of that he was pooping a lot of bile. He said it wasn't a problem unless my son was gassy/fussy or not gaining well (he didn't have either of these problems). I nurse my youngest the exact same way as I did my oldest and he has never had green poop. Go figure.
that is very interesting because he does seem to poo all day long and usually it is when he wakes up to begin nursing or after one side. But he is not really fussy so I am going to assume everything is ok. It is annoying to have to change him so often but oh well I guess he is healthy.