My sister had a baby July 25th and has been breastfeeding exclusively, though my nephew was being a little difficult with latching on and lost weight so she stayed in the hospital an extra couple days. The birthing center had a lactation consultant which really seemed to help and I hope that more hospitals follow that trend to try and avoid formula if at all possible.
She has lost over 34 pounds since then, and his goal was to be back at birthweight (6lbs, 12oz) by his well baby checkup last week. The little piglet was 8.5 lbs!
I haven't heard about any problems with feeding while not at home yet but she works from home and that is likely a factor in not having issues yet. Sounds like a quick way to lose weight if it wasn't for the whole infant issue.