What is the Pre-Op Diet for Weight Loss Surgery?

General and Bariatric Surgeon

Hi I’m Dr Erik Lough answering common questions that patients ask me about general and weight loss surgery. Today I answer the question, what is the pre op diet for weight loss surgery? The preop diet is a low carbohydrate / high protein diet for Two weeks prior to the operation. The purpose of this diet is to use up all the stored carbohydrate in your liver known as glycogen. Depleting your liver’s carbohydrate stores shrinks the liver, which makes a more ideal situation for your operation. Anatomically the liver is basically laying on top of the stomach and small intestine which is precisely where I need to get to in order to perform a gastric sleeve, gastric bypass, or duodenal switch. If the liver is too big and I can’t retract it out of the way, I may not be able to safely complete the surgery due an increased risk complications or bleeding from the liver itself. Worst case scenario, it might be safer to abort the procedure for now and come back to try again at a later time when we can get the liver to shrink more.

For 2 weeks prior to surgery, the main focus will be on limiting carbohydrates to 30 grams per day. A patient can do this by shooting for 70 grams of protein, 30 grams of carbs, and fat in moderation by avoiding fried foods, butter, fatty meats, and lastly avoiding alcohol. You may also wanna use protein drinks or bars during this time, just make sure you read the nutrition label to confirm it is low in carbs. We provide our patients a sample grocery list and menu for 7 days that can be repeated to make it to 14 days with foods like meat, cheese, nuts, eggs, peanut butter, and vegetables. Avoiding excessive bread, cereal, pasta, fruit and milk is key.

The preop diet is also a great time to practice your new dietary guidelines such as chewing 30 chews per small bite of food, avoiding liquid calories, avoiding drinking at meal times, and hydrating with sugar free liquids in between meals.

Some patients are worried that the whole 2 weeks preop diet is liquid but that’s not actually true. Only the one day immediately before surgery requires a sugar free liquid diet. Then you have nothing to eat or drink after midnight before surgery and your liver will be nice and shrunk just in time for the big day.