obeselete
Obeselete is a term for people who have become useless because they are fat. It can be used as a noun or an adjective. This could be because they are too fat to move, or because they are too fat to do their given profession, etc.
"Britney Spears was never good at singing but, some say she had something of a body. Now she is obeselete."
"That obeselete is so fat he cant fit out of his house."
"That obeselete is so fat he cant fit out of his house."