Bariatric Surgery Pre-Op Diet Guide

The purpose of this nutrition guide is to help shrink your liver prior to surgery by depleting stored glycogen. The goal is to consume 2-3 meals of solid, macronutrient-rich foods per day. These whole meals will stay in your stomach longer keeping you full. In addition, use protein shakes as a supplement snack, generally, 1-2 protein shakes per day.

Pre-Op Diet Guidelines Based on BMI

Start the pre-op diet based on your current BMI.

  • 30-32 =  2 days clear liquids only

  • 33-39 = 1 week pre-op diet including two days of clear liquids

  • 40-45 = 2 weeks pre-op diet including two days of clear liquids

  • 46-49 = 3 weeks pre-op diet including two days of clear liquids

  • 50-59 = 6 weeks of pre-op diet including two days of clear liquid diet

  • 60 plus = 8 weeks pre-op diet including two days of clear liquid

Bariatric Surgery Pre-Op Diet Guidelines Based on BMI

General Overview

  • 1 – 2 protein shakes per day -You may purchase these in any health food store or many grocery stores. Please be sure it contains at least 20 grams of protein per serving.  Sugar should be 5 grams or less.

  • You can eat as many raw or cooked non-starchy vegetables as you want (no potato, corn, or peas)

  • Two 4 – 7 ounce servings of lean protein (chicken, turkey, fish, lean ground beef)

  • 1 – 2 servings of healthy fat (salad dressing, olive oil, nuts, avocado, olives)

  • You can add ½ cup of frozen berries or ½ banana to your protein shake

  • You can make your shake with unsweetened vanilla almond milk or unsweetened coconut milk (NO regular milk: too much sugar)

  • NO bread, rice, pasta, refined grains, tortillas, sauces with sugar, and no dairy (milk, yogurt, cheese)

  • NO alcohol two weeks prior to surgery

  • Weight Loss Magic Soup Recipe – Great Vegetable Soup

  • Do NOT smoke 30 days prior to surgery

  • OPTIONAL: Start taking a probiotic 6 weeks prior to surgery or as soon as possible. You want one that has a minimum of 50 billion units and the more strains the more effective and discontinue 2 weeks before surgery.

Behavior/Lifestyle Changes

  • Discontinue ALL consumption of Dairy, Starches, Sugars, Desserts, and Fruit (with the exception of 1/2 cup berries or 1/2 a banana daily)

  • Discontinue drinking ALL caffeine 2 weeks prior to your surgery date. Caffeine is a diuretic, may cause dehydration and is acidic. You may drink decaffeinated coffee. Please ensure to stay hydrated.

  • Discontinue ALL carbonated beverages (sparkling water is okay)

  • Avoid: Ginseng, Ginger, Garlic and Omega 3 supplements. These increase bleeding risk. You may consume small quantities of garlic and ginger in cooking

  • VERY IMPORTANT: Begin the practice of NOT drinking 30 minutes prior to/during/post meals. This should become a LIFELONG HABIT.

14 Days Prior to Bariatric Surgery

  • Stop ALL vitamins and herbal supplements 2 weeks prior to surgery (based on your surgery date). With the exception of your prescribed medication. This will need to be discontinued day of surgery unless otherwise approved by your surgeon.

7 Days Prior to Bariatric Surgery

  • Some medications may need to be discontinued before surgery depending on the instructions of your SURGEON.

  • Specific medications to STOP: Coumadin, ANY ANTICOAGULANTS, OR BLOOD THINNERS Plavix, Aspirin, Ibuprofen, Motrin, Advil, Nuprin, Aleve or any other nonsteroidal anti-inflammatory medication. *Remember this also includes baby aspirin and most arthritis medications. As these can cause stomach irritation and possible more bleeding postoperatively.

  • If there are any medications you need to stay on, talk directly with our surgeon liaison.

  • Discontinue birth control and supplemental hormones (IUD’S & IMPLANTS ARE TOTALLY SAFE and do not need to be removed).

For Diabetes Patients

  • May continue to take medication up to the day of surgery. Be mindful, medications and amounts may change due to diet and weight loss change prior to surgery.

  • MUST consult with their doctors about medication use.

  • MUST check sugar levels at home. If sugar is above 150 call your primary care physician immediately.

2 Days Prior to Surgery – Begin Clear Liquid Diet

  • Consume only clear liquids: Apple or other clear juice without pulp or carbonation. (Honest Kids Juice is the lowest in sugar (10 g. per serving. If you get regular juice use 100% real juice and dilute 60/40 with water)

  • Clear broths: Chicken, Vegetable, or Beef.

  • Water or Flavored Water.

  • Sugar-free drinks such as crystal light, vitamin zero water, Powerade zero.

  • Sugar-free popsicles and sugar free jello

8 Hours Prior to Bariatric Surgery

  • Absolutely nothing to drink after the midnight preceding surgery or 8 hours prior to your surgery.

  • Absolutely NO medications unless directed by the doctor. (If you have been pre-approved to take any medications by your physician leading up to surgery, you may take small sips of water for swallowing.)

  • Please bring ALL your prescribed medications (whether you are currently taking them or not) in properly labeled pharmaceutical bottles for documentation during Pre-Op testing. Do NOT take any medications after surgery until you have consulted with the doctor(s) and gotten approval.

Pre-Op Diet Guidelines

Here is a sample meal plan to help you get started on the pre-operative diet.

Here is an ‘example’ of what your day could look like:

  • Breakfast: Options include 2 Whole Eggs, 1/2 an avocado, 1 Cup of Spinach (Raw or Cooked), or 1 Protein Shake

  • Mid-morning snack: 1 Protein Shake (limit 1-2 per day)

  • Lunch: Raw or cooked vegetables (you can add one TBSP olive oil or butter spray to veggies) and 4 oz.  lean meat. Example: 4 oz (110g – 170g) of lean protein, 2 Fist size of vegetables (fibrous carbs), 1-2 thumb size of fats

  • Dinner: Salad with Protein (chicken, fish, egg, etc.), a small amount of no or low sugar dressing (preferably olive oil & vinegar or Lemon)

  • Evening Snack: Apple slices with Almond Butter or Vegetables with Hummus

  • You may also add 1 TBSP chia seeds to your shakes or take psyllium husk to help you stay satisfied throughout the day.

  • * Patients with higher or lower BMI and/or other medical conditions may be prescribed other dietary prerequisites in addition to the above pre-op diet.

  • * You may at this time drink other drinks as long as they have NO SUGAR

Approved Proteins and Vegetables

Grass-Fed MeatCelery
LambBok Choy
90/10 Lean cut beefMushrooms
Lean pork
(Pork Tenderloin)
Wild Game
(Buffalo, Elk, Venison)
Organic PoultryAsparagus
Chicken BreastTomato
Eggs / Egg WhitesCauliflower
Egg SubstituteBell Pepper
Wild Caught SeafoodEggplant
ClamsBrussel Sprouts
LobsterGreen Beans
ScallopsBlack Beans
Protein AlternativesChickpeas
Vegan Protein PowderSpinach
Whey Protein PowderCucumber
Nuts & Seeds
Beans (all varieties)
Impossible Burger
Fairlife Milk

Approved Fats

Healthy Fats 

  • Avocado
  • Olive Oil
  • Nuts (Limit to a handful per serving)
  • Nut Butters (1 TBSP per serving)
  • Chia Seeds
  • Flax Seeds
  • 85% Beef
  • 90% Bison
  • Salmon
  • Hemp Seeds
  • Whole Eggs

Recommended Protein Powders

Ideally, you want to get your protein intake from real foods. However, if you need to supplement with protein powder, we recommend sticking with plant-based proteins. Whey isolate is okay and you also may have premier protein shakes. Choose a protein shake that is high in protein 20 grams or more and low in sugar <5 grams.

Here are a few of our favorites. You can find them on Amazon.

  • Vega One Organic All-in-One Shake
  • Vega Sport Performance
  • Nuzest Clean Lean Protein – Premium Vegan Protein Powder
  • Naked Pea Protein