You want the fat/oil to get into your system quickly so you get a big response from the liver and gall bladder. A big meal will take up to several hours to digest. If you want to do it with food, then do as Hanna Kroger (of Kroger Herbs) used to recommend...eat a large bowl of real whipped cream. Being a single food item, and mostly fat, it acted similarly to olive oil as far as response from liver & gallbladder and as far as being a quick response vs. taking several hours for meal to digest.