I didn't get an option. 1 week of 2 protein shakes and a meal, 1 week of 4 protein shakes and all clear liquids the day before surgery. On the two week pre-op, I can also have sugar free popsicles, broth, chrystal lite, tea, anything without sugar. The meal is no more than 300 calories - 6oz of lean meat or fish and 1/2 cup of veggies. This is supposed to make the transition to the new way of eating easier and help the body become adjusted to runniing on a lower caloric intake, plus shrink liver and belly fat to create more room for the surgeon. My BMI is 39.5. My Dr said if I just follow the plan exactly as he gave it to me I should be fine. He was just voted one of the top dr.s in the field by his peers and has been doing this exclusively for years. I have a friend, however, who is having a gastric bypass 2 days after me at a different hospital in town and has no post op diet. Just clears the day before surgery. Go figure.