I did 6 months without a break on LighterLife with no problems whatsoever. I know that on some VLCD they suggest a milk week on week 13 - adding milk to the shakes but I reckon it is rubbish and not needed. If you feel you have to stop, whatever you do stay away from carbs - just ead low carb veggies and salad along with steak, chicken and fish. That way you will stay in Ketosis and not feel the hunger.