I googled "south beach diet pinto beans" and from what I understand you can eat them in phase 2 but not phase 1. Looking around it seems that older versions say leave the beans till phase 2, but newer versions say pinto beans are okay for phase 1.
Sooo yeah.... lol- take with that what you will- I say if you want to eat them then go for it
I tried to post links but they are being blocked for some reason.