Grease content causing obesity? (9)

'obesity?' is the definition.
The answer and definition can be both human attributes as well as being singular nouns.
Perhaps you can see an association between them that I can't see?

'grease content' is the wordplay.
I cannot really see how this works, but
'grease' could be 'fat' and 'fat' is located in the answer.
This may be the basis of the clue (or it may be nonsense).

'causing' acts as a link.

Can you help me to learn more?