Bariatric Surgery Pre-Op Diet Guide


The purpose of this diet is to help shrink your liver prior to surgery by depleting stored glycogen. How we achieve this is the elimination of processed sugars and foods.

This is the guideline for a pre-op diet based on your BMI.
Your surgeon may modify this.

  • 30-32 = 2 days clear liquids only
  • 33-39 = 5 days of pre op diet and two days of clear liquids
  • 40-45 = 2 weeks pre op diet and two days of clear liquids
  • 46-50 = 3 weeks pre op diet and two days of clear liquids
  • 51-60 = 6 weeks of pre op diet and two days of clear liquid diet
  • 61-70 = 8 weeks pre op diet and two days of clear liquid

Before Surgery

  • Do not smoke 30 days before surgery
  • Start taking a probiotic six weeks before surgery or as soon as possible. You want one that has a minimum of 50 billion units, and the more strains, the more effective.

Follow Pre-Op Diet below:

Protein powder/drinks:

You may purchase these at any health food store or many grocery stores. Please be sure it contains at least 20 grams of protein per serving. Sugar should be half the grams or less than protein- if you have 20 grams of protein, it should have less than 10 grams of sugar.

General Overview:

  1. 2 – 3 protein shakes per day
  2. You can eat as many raw or cooked vegetables as you want
  3. 2 – 4 oz. servings of lean protein (chicken, turkey, fish, lean ground beef)
  4. 1 – 2 servings of a healthy fat (salad dressing, olive oil, nuts, avocado, olives)
  5. You can add ½ cup of frozen berries or ½ banana to your protein shake
  6. You can make your shake with unsweetened vanilla almond milk or coconut milk (no regular milk- too much sugar)
  7. No bread, rice, pasta, refined grains, sauces with sugar and no dairy (milk, yogurt, cheese)

Since you can have as many veggies, here is a great soup you can make to eat when you are hungry:

Sample Meal Plan:

Breakfast: 1 protein shake

Mid-morning Snack: 1 protein shake

Lunch: Raw or cooked vegetables (ok to add one TBSP olive oil or butter spray to veggies) and a minimum of 4 oz. Lean meat. Example: Tilapia with baked broccoli seasoned w/ olive oil and slivered almonds

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:1 protein shake (if needed).

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

Behavior/Lifestyle changes:

  • Discontinue ALL carbonated beverages.
  • Discontinue ALL beverages with caffeine.
  • Begin a routine exercise program (consult with your physician first).
  • Cut food into SMALL pieces and practice chewing foods VERY well.
  • Discontinue ALL over the counter Herbal supplements.
  • VERY IMPORTANT: Stop drinking 30 minutes prior to eating and DO NOT drink until 30 minutes after a meal.

7 Days Prior to 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 non-steroidal anti-inflammatory medication. **Remember this also includes baby aspirin and most arthritis medications. As these can all cause stomach irritation and possibly more bleeding postoperatively.
  • If there are any medications you need to stay on, talk directly with your coordinator to get an ok from your surgeon.
  • Discontinue Vitamin E
  • Discontinue birth control and supplemental hormones (IUD’S AND IMPLANTS ARE TOTALLY SAFE and do not need to be removed).
  • For a headache or minor pains, you may use Tylenol.
  • Do not take any herbal medications/remedies.
  • Diabetes Patients:
    • May continue to take medication up to the day of surgery. Be mindful, drugs 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.

3 Days Prior to Surgery

  • Complete bowel prep by taking laxative (only once) on the 3rd night prior to surgery.

2 Days Prior to Surgery

  • 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 milk use 100% real juice and dilute 60/40 with water)
    • Clear broths: Chicken, Vegetable, or Beef.
  • Water or Flavored Water.
  • Need to have 2 Greek yogurts per day (may be flavored but no pieces of fruit, it also has to have more protein than sugar. Plain Greek yogurt is your best option or something similar) – this helps with post healing and providing healthy INTESTINAL FLORA bacteria in your gut.

8 Hours Prior to 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.