Hi Julia, I'm not sure if this helps or not, but I'd imagine if you want to put yourself on a liquid diet a couple of days before the preparation day, you could drink V-8, eat yogurt and jello. And there are the nutrition drinks like Glucerna (though I don't know how your blood sugar would react to that.) I would imagine all that would not bulk you up, and I guess they would not spike your blood sugar. You didn't say if you are on meds, so if you are, you'd probably have to adjust them with this temporary change of diet. Then, follow the special instructions the day before the exam. Yup. Jello! Good luck!