As long as you get back on the program right away you shouldn't have too much of a problem. My last "deviation" cost me 3 months so I speak from experience, LOL. Besides the weight gain, I constantly felt sluggish and lethargic from eating all those carbs. I have been back on track for the past 9 days - the first three were hard - but after that it became easy again. My energy is starting to return and I have lost some of the weight I had gained. Let me know if I can help in any way.