If you saw how many stones come out and all the different sizes and even the color, you'd know they were not just the oil. It is absolutely amazing what comes out of your body. I've done about 5 Liver Flushes now. The first was with the assistance of colonics and I got out thousands of stones- all different colors and sizes and shapes. The next 3 I did at home and were not as successful but I still got out anywhere from 50-300 stones of different sizes and colors in each of the flushes. The one I did this Friday was amazing!! I only got out about 350 stones but they were the green ones and some of them were huge, some like the size of peas, some like capers and many even smaller. When you squeeze them, they do feel like fat but they don't feel like olive oil- it doesn't leave the same residue on your fingers. Olive oil feels oily yet kind of light. You can wash it off. The green residue from the stones feels very heavy- more like a heavy grease and you really have to wash several times to get it off your hands- it's actually pretty gross. Also- since your whole body is completely flushed out when you drink the olive oil, I'd wonder how the oil coagulates (spelling?) so quickly and turns green and solid when it comes out. Some come out as quickly as an hour after- some keep coming out for days (some people say even months but I haven't had that experience). But anyway- I know this is a very long answer to a short question, but my belief is that they are definitely stones and not the fat from the olive oil. I hope you try it- it's truly an amazing experience!! And good luck on The Master Cleanse. I finished mine a few months ago- it takes a lot of willpower!!