i dont think you have to have an empty stomach. i usually feel more nauseas if my stomach is empty. i usuallly take it an hour (or maybe 2 after) i eat. i have heard stories about meat protien interfering with mms and to wait about 2 hors from meat protien--- but i dont really know how accurate that info is. one of the suppliers on jims site mentiioned it to me. but like i said, i eat about an hour or 2 before mms, if i can (but nothing with added vit c nor do i eat oranges right now). but thats just me - i seem to be getting good results this way.