Be aware there may be some unpleasant physical side effects. When the body has been deprived of food for so long, reintroducing normal eating habits are a shock to the system. Side effects include diarrhea, nausea, weakness, sleep disturbances, a heightened sensitivity to cold, a weak bladder, and constipation. Be aware going in such side effects may occur, but view them as signs you're on the path to a healthier, happier you