adj. Excessively rich, fattening, gluttonous, or unhealthy, often referring to food. Also, the feeling one has after consuming such food. Fattycatty can be used as both a positive and a negative.
Negative-- wife: "Let's get a pizza for dinner tonight"
husband: "Nah, I'm feeling a bit fattycatty.
I had pizza yesterday and a philly cheesesteak
Positive-- "This philly cheesesteak is the bomb. It's fattycatty like a cheesesteak should be"