Carb up day to stay sane. the 4th and 5th day on a CKD are the worst, you will be wanting a carb up day because you most likely feel like shit and your muscles will suck up the carbs like crazy..
for most people a carb-up is just a pig-out-on-junkshit day - that's where the problems arise.
a controlled refeed is of true benefit, while pigging out is completely mental; I know of a few people who have developed binge eating disorder as a result
if you cannot control your refeeds then you are putting yourself in a vicious cycle by undertaking CKD, try something else, more balanced