Of all the carb heavy foods to cut out, I'd cut out rice 2nd to last (potatoes absolutely last). What makes it "bad" to you?
The sources I've been reading are neutral-to-mildly-unhappy about it (Archevore, Bulletproof, Mark's Daily Apple, 4-Hour Body), and I eat a lot of it.
As I understand it, Lent is a holiday where we celebrate the scientific method by changing exactly one variable in our lives for 40 days. This seems like a convenient Schelling point for rationalists to adopt, so:
What variable are you going to change for the next 40 days?
(I am really annoyed I didn't think of this yesterday.)