I dont know you, your diet or how hard you work out but I have found for me that I dont get set back at all. When I do my 13 days of super clean eating and training I can cut pounds of fat (maybe 7 or 8) and by day 13 I am pretty wore out physically and mentally. Yesterday I woke up at 7 and ate a damn near a dozen donuts, a kit kat and 3 toquitos from 711. I went back to bed for 2 hours and then went out for lunch with some buddys and had a double bacon cheeseburger with fries and a shit tonne of gravy. I was so stuffed after that I could hardly move. At around 430 I went to the gym and did a chest workout and some pretty decent cardio for how full I still was. Right after my workout I ate a large popcorn chicken from KFC with a bunch of gravy. After that I went to our local bar and picked up a case of beer and drove over to my cousans place. After a couple beers I was still really full but I knew I could make a little room so I looked in the fridge and to my delight there was a big old bowl of taco salad in there. I ate the whole bowl. After another beer or two I was ready to party but nobody wanted to go out so I just sat in my cousans hot tub and finished my case off. I crashed on the couch and was full as f*ck and drunk as f*ck. This morning I woke up at 9 feeling a little hung over but not bad....Yeterday morning after 13 days of strict diet and training I felt tired, wore out, I craved bad food, I was metally drained, and lean as could be...Today (now that my hang over is gone) I feel fresh, restored, I crave no junk food, I have a shit load of energy and I feel even more lean than I did yesterday....Eating like this will NOT put a damper on getting lean if you do it right. If anything it helps...Im gonna go another 13 days and do it all over again. Im not trying to say your wrong and you may be mega ripped and lean doing it the way you do.. but I have always found that these guys who say a cheat day ruins progress seem to be the guys that eat "kinda good" instead of really good for a few days or a week, and then go out and eat like that. They dont allow their bodies to actually burn off fat on their "cut" days and then they go pig out and gain fatty weight. Dont blame the cheat day, blame your lack of discpline on the days where you actually try to lose body fat.