1. The grape fruit/lemon is for citric acid , I believe. What that does I don't recall, but that's the active ingredient.
2. I have never heard anyone say you should lie on your left side, the right is because that's the side your gall bladder and liver are on (in most people anyway). Me I can't comfortably lie all night that way, so I compromise and do it for 30 min. after I finish the olive oil/grape fruit juice. You can lie on your back when you sleep, I don't think it hurts the results that much.