One whose diet consists of mostly cake and other pastries. Most eat fruits as well and exercise for good measure(and to prevent becoming fat, as that is unsightly).
Jane, the proud cakeatarian, used her weekends to eat lots of cupcakes and then promptly play tennis with friends afterwards.
Joe: I'm switching to Cakeatarianism, healthy diets can go fuck themselves.
What? JOE is evolving!
Congratulations! Your JOE evolved into FATASS!