Pre-Op Liquid Only?

I just have a question, I am wondering why the pre-op liquid diets?  And why the variances in how many days to follow it?  I surgeon didn't give me those directions.  I only have the day before surgery that I have to do liquids.  

I was told only people with a BMI over 50 are required to do a pre liquid diet to shrink their liver. I didn't have to do one either.

Oh, ok.  Thank you.  I was so curious.

The reason for the preop diet is so you can shrink the liver therefore making the surgery safer for you to undergo. Surgery is more risky with an enlarged liver.  Yes, all surgeons have different guidelines as to how many days or even weeks one has to follow the diet. I know some doctors determine how long your liquid diet will be based on your BMI. The higher your BMI, the longer the preop diet.  

Aside from shrinking your liver, it gets your brain and body ready for what happens after surgery. Your new diet and lifestyle.

I have never found a good explanation of the value of the pre-op liquid diet. The liver shrinking thing (which itself is a debatable topic amongst the docs), requires a low carb diet, but that can be done without going the liquids only route. Some docs indeed do a low carb diet - meat and low carb vegetables, etc. as their pre-op diet while some do some combination of the two - protein shakes along with low carb meals (while others do nothing at all.) I never found the excuse of practicing for post op eating all that satisfactory, as your body will tell you what you can tolerate - you aren't going to want much else until you are ready (which might be a few weeks, or just a couple of days -YMMV.)

If someone finds of a good explanation for these liquid diets (other than the liver shrinking thing,) I would love to hear it.