I too have noticed that babies with infrequent BMs are usually roly-poly.  I
figure that their bodies are using everything up so efficiently that there
isn't much waste left over.  The key is when does the infrequent BM begin?
and is the baby gaining appropriately?  IMO the infrequent BMs don't become
evident until after 6 weeks of age and baby is rapidly gaining.  In first
days or weeks IMO it is a sign of insufficient intake!
Pat Young in SNJ, USA