I am of the school of thought that says that it is impossible to overdo it on a free day, as long as it is ONLY ONE free day a week. There is no way the body will erase 6 days of progress in one day. The stomache and esophagus simply will not allow it. Your stomach may be temporarily bigger during the day but that is because of the undigested food. It will go away by the next day. If you are paranoid about overdoing it on the free day, have a very intense weight training workout early in the morning. That will help to minimize any chances of fat gain. Also, you might try not to combine carbs and fats in your cheat meals. You can have a little protein and tons of carbs in one meal, or a little protiein and tons of fats in another meal. Just dont combine carbs and fats - saturated or unsaturated. Honestly, I just throw all the rules out of the window on the free day. I do try to make sure I am getting a little protein and tons of carbs, but I dont worry about the saturated fat. I just conciously try to gorge myself. I am of the belief that the cheat day actually helps you lose fat in the long run because it helps to reprime your leptin levels and other fat burning hormones.