Got sick for a day. Last 3 days I buried myself to catch up; I'm up 6 pounds and wanted to drop some so I put in some big z2 rides running a -400 calorie deficit. Nothing out of the ordinary. The problem was on Tuesday I didn't add up the food I tracked, rode a 1100 kj ride and got sick. Turns out I had 300 calories net that day (oops).
Next day I had to eat so much it almost negated all that. I've learned I can't go under -400 over maintenance and when I do I have to eat in a few days to make it up.