Leptin
Obviously you need to read up about leptin. Stick to a clean diet too long and your body gets accustomed to it. This is why we use carb-ups and refeeds, etc, to stop your thyroid from grinding to a halt and in turn slowing down and ultimately killing your metabolism. A cheat after long, arduous clean eating WILL benefit you and at least give you full glycogen stores to truly push yourself at the gym the next day. Of course cheating selectively, ie not combining high GI starch with bad fat sources might cause some to react more negatively than others, but by piling on the calories you force your body to switch metabolism to high gear and attempt furiously to burn the excess calories. A cheat meal WILL fuel your metabolism, and if you've been eating clean, you have NOTHING to worry about, your cheat meal will actually BENEFIT you! Drink plenty of water with your meal, eat plenty of vegetables to help with digestion, and if you're extra paranoid, maybe take in 1g of R-ALA prior to your meal.
I can personally tell you that after huge cheat meals following long periods of clean eating I HAVE woken up with much fuller muscle bellies, and the strength and pump you will receive in the gym will be unbelievable, especially if you have been on a very low carb diet. Just revert back to eating clean the day after and you have absolutely nothing to fear.
I have no idea how any of you get the concept that ONE CHEAT MEAL on a SPECIAL HOLIDAY WHERE EVERYBODY EATS will ruin your diet and your physique, some of you need to stop being so damn obsessive and live the life you've been given...jeez, I can't begin to imagine what your friends or parents think of you if you can't live once in a while. Life isn't all about bodybuilding and getting huge/ripped.
Peace.
