Cirrhosis an ascites? Caput medusae?
It's actually a condition called Tauntaun Syndrome.
nobody is curious as to what is inside that belly, or at the least if he is ok?
Please see illustration below.
I wonder if there is any kind of procedure to reduce the size of his stomach?
There is. The procedure was pioneered on the ice-planet of Hoth. It's pretty straightforward, but requires the use of specialised equipment, e.g. a light-saber... (and about 500 sutures afterwards)