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Your Pre Bariatric Surgery Diet

It’s not uncommon to want to visit your favorite restaurants and to eat your favorite foods before surgery. It’s important however to practice your new healthy relationship with food by eating healthy portion sizes and foods.

Our surgeons require you to follow a modified diet for two weeks or more prior to surgery to prepare your system for the transition. Bariatric surgery requires you to make life-changing adjustments to your diet before and after surgery. Adopting a healthy, low calorie diet plan prior to surgery is the first step in your journey to lasting weight loss, and one that prepares you for your new dietary restrictions post bariatric surgery.

The following information is provided for general purposes only. Please consult with your doctor about your specific health needs.

The Purpose of a Pre-Bariatric Surgery Diet

  • Reduce body fat around your stomach and liver, as well as shrink the liver itself. If the liver is too large bariatric surgery may have to be postponed or performed as an open procedure (instead of laparoscopically). Your stomach and liver are near each other and a large liver can interfere with surgery.
  • Improve surgical outcomes and recovery. By reducing fatty triglycerides from around the liver and spleen patients typically experience decreased complication rates.
  • Increase protein intake, which can help preserve and protect muscle tissue post-surgery.
  • Prepare you for your new post-surgery diet (reduced calorie, high-protein, low-fat, low-carbohydrate).


Avoid overeating in the days and weeks leading up to your surgery date and start following a diet plan that is similar to what your post-surgery diet plan will be. You can still eat that special meal you’ve been craving but have a protein shake or another low calorie option for your other 2 meals that day.

Pre-Bariatric Surgery Weight Loss Increases Safety

Patients who lose weight prior to surgery typically see lower complication rates. In some instances you may be required to lose weight before surgery if you wish to have the procedure done laparoscopically, rather than as an open surgery. The purpose of losing weight before weight loss surgery is to reduce body fat in the abdomen region, especially in and around the liver. Reducing the size of the liver increase patient safety and typically shortens the duration of laparoscopic procedures. Your bariatric surgeon may postpone surgery if your liver is too large.

Pre-Bariatric Surgery Nutrition

You can expect your pre bariatric surgery weight loss diet to be high in protein, but low in calories, fats, and carbohydrates, especially refined sugars and saturated fat. The pre-surgery diet usually ranges from 800 to 1200 calories per day with about 70 to 120 grams of protein each day. Many surgeons require a full liquid protein diet for two weeks prior to surgery. You will also be asked to start vitamin supplements to ensure your body has the nutrients necessary for recovery and health.

Bariatric Surgery Pre-Op Diet

Before undergoing weight loss surgery, your bariatric surgeon or dietitian will explain your pre-surgery diet. Although specific diet suggestions can vary from patient to patient, procedure to procedure, and surgeon to surgeon, there are many dietary and nutritional guidelines common to most weight loss surgery patients. The following guidelines should not take the place of your surgeon's directions, which are based on your health, weight, and type of weight loss surgery.

General Pre-Bariatric Surgery Dietary Guide

  • Begin protein supplements (protein powder, protein shake)
  • Decrease all fats (fatty meats, fried foods, whole milk products, etc.)
  • Decrease sugary foods (sweets and soda)
  • Decrease high carbohydrate foods (bread and pasta)
  • Stop smoking
  • Avoid alcohol
  • Avoid binge eating
  • Don't use certain over-the-counter medications and prescription medications (speak with your doctor for specifics)


It is important to follow your surgeon's pre-surgery dietary and nutritional guidelines. Not only will your pre-surgery diet help prepare your body for surgery and improve the outcome, but it will help you adjust to the changes you will be expected to make about food following weight loss surgery and for the rest of your life. Do not start on any pre-bariatric surgery diet without the approval of your doctor and surgeon.