What I've read is if you go off the diet (cheat) on Saturday, then start back on it Sunday, it may be Tuesday or wednesday till you start felling better. The diet has a built in reward and punishnent system. Cheat and you feel fatgued, stay on it and you don't have the food carvings. What happens - You cheat then your bodey switches over and starts burning the carbs / sugar for fuel which gives you a boost, then you start back on the diet and you have burned up the carbs / sugar so you start feeling fatigued. It then takes about two days for your body to say HEY I need fuel but I'm not getting any and you start putting out FMS ( Fat Mobolizing Harmone) which start burning your fat. Atkins also suggest taking vitimans which help allot. I take multi Vitiman, 1000mg of Vitiman E, a Multi B complex vitiman and a extra vitiman C for good measure. But the main thing is to just stick to the diet and your goal, don't watch the scales because with allot of water intake the wieght goes up/down. The next thing you know, your wearing a size smaller in clothes. Hope this helps.