You breathe this way when you have eaten very well and your belly feels full, heavy and pushed-out. Because it is already pushed-out, you cannot breathe into your belly, and probably are breathing into your chest. Your abdomen is very relaxed which is not good for posture, but in some cases can be good if you are a singer. A relaxed abdomen is a prerequisite for a good sounding voice and it’s very hard to sing well with a tensed abdomen.