Its not so much a gravity thing. It is more related to what digestive enzymes go with what foods and do they cancel each other out necesitating longer digestion times. Water should never be drank with a meal or for a period after as it diultes the gastic acid and cuases food to pass into the intestine not properly broken down, especially proteins. I recommend reading up on the concept of proper food combining. You can search natural hygeine for more on this. Harvey Diamond covers food combining in his book "Fit For Life One".