Everything about Pre-Bariatric Diet You Need to Know

Have you qualified for bariatric surgery? If the answer is yes, then it’s time to follow a liquid diet and read this article. By the end of this article, you’ll know what to expect from your surgery and how to help yourself.

All the weight loss surgeries like gastric sleeve, gastric bypass, gastric band, mini gastric bypass, and gastric balloon require you to go on the liver shrink diet before.

You may have to follow the diet 3 – 10 days prior to the surgery. This duration will depend on your BMI.

During this time, you have to follow a strict low-calorie diet.

What is the pre-bariatric liquid diet?

The pre-bariatric liquid diet is also called the liver shrink diet. Here’s why you should follow it and what it does.

  1. It helps shrink your liver before bariatric surgery.  A low-calorie diet is a preferred way to shrink the size of the liver successfully.[1]J. Van Wissen, N. Bakker et al. “Pre-operative Methods to Reduce Liver Volume in Bariatric Surgery: A Systematic Review” Obesity Surgery (2016) 26: 251-256
    View in Article
  2. It is easier for your surgeon to push the liver out of the way during surgery.
Our US-registered dietitian answers a client’s query

Question – How long will I have to follow the pre-op bariatric diet?

Answer – Generally, the pre-op weight loss surgery liquid diet should be religiously followed for 3 days to 3 weeks, depending on the individual.

(Disclaimer: This is general information based on suggestions by our Mexico bariatric program and not intended for medical advice. Please consult your doctor for an assessment.)

Why should you follow the pre-op bariatric diet?

The liver shrinking diet helps your surgeon during the surgery. It is most important for a successful surgery.

  • It gives room to the surgeons to use their instruments.
  • It gives them a better view of the stomach.
  • Low-calorie food also helps you lose weight.

The good news is that this liquid diet before surgery is not forever. It is just temporary.

Please note that the main purpose of this diet is to shrink your liver and to lose weight.

Beverages and foods that you can consume on this diet include:

  • 60-80 gm of protein with protein drinks
  • Low fat or non-fat milk
  • Decaf coffee or tea
  • Sugar-free or diluted juices including vegetable juice or tomato juice and cream of wheat or oatmeal
Oatmeal Consistency; WLS Special

The night before surgery, you have to stop eating or drinking anything around midnight.

How to Follow the Diet

According to Cleveland Clinic [2]“Nutrition Manual.” Cleveland Clinic – Bariatric and Metabolic Institute
View in the Article
, the pre-op bariatric diet should commence 2 weeks before surgery. The clinic states that:

  • In the first week of the diet, have protein shakes (low in sugar and high in protein) in one meal out of the three.
  • Nutritional supplements, Nonsteroidal anti-inflammatory drugs (NSAIDs) are strictly not recommended.
  • In the second week, stop all solid foods. Replace all your meals with only protein shakes and clear liquids. Here are some calorie-free options for a pre-op liquid diet.
  • 24 hours before the surgery, a full-fledged clear liquid diet is to be followed.
  • Do not eat or drink anything after midnight the night before your surgery.

The main idea is to have a liver-shrinking diet rich in protein and low in carbs so that the excess fat stored in the liver is burned for energy as opposed to muscle tissue.

Side effects of the Pre-Bariatric diet

When you put yourself on the liquid diet, it is a drastic change for your body. Preparing yourself for these changes beforehand can take a lot of stress off. We’ve compiled a list of the issues you might face and how to take care of yourself.

Nervousness and Anxiety

It is common to experience nervousness before bariatric surgery. Now what happens a lot of the times before the operation is that people exhibit the last supper mentality, is what I like to call it, and so:

  • You may have feelings of anxiety
  • You might be worried that you are never going to eat again
  • You are never going to enjoy some of your favorite foods, and it is 100% normal to feel that way.

You don’t need to worry at all. You’re entering a new positive phase of your life.

Gradually you can do everything you once did, and more! You’ll be able to add a lot more to your life when you shed those extra pounds.

Emotional Eating

You could feel the need to constantly eat snacks and sugary foods.

  • You are snacking more because of anxiety.
  • You’re not hungry but feel the need to eat to fight emotional turmoil.

This will make your liver enlarged which is not good for the surgery. Your surgeon won’t be able to get a clear view of the liver.

Here’s how you can help yourself

Other side effects
  • Migraines because of reduced calorie intake
  • Lightheadedness
  • Dizziness
  • Cold sweats
  • Trembling

How to Overcome the Side-Effects of Pre-Op Liver Diet?

Every problem has a solution, and so do the side effects of the liquid diet. 

Decrease caffeine intake

Gradually decrease caffeine intake. For example – if you are in the habit of having two cups of coffee, start slow, maybe cut it back to one cup of coffee and then the next day to half a cup of coffee and then a quarter cup of coffee and slowly decrease it, that helps with that headache, that withdrawal.

You may have slight migraines if you suddenly stop all caffeine. If you’ve stopped caffeine, then try adding just a little bit of it to your diet.

Stay hydrated

The second potion is you are probably dehydrated, so:

Check blood sugar

This is important for diabetics. Diabetes is the reason for lightheadedness, dizziness, cold sweats, and shaking.

Check your blood sugar more frequently if you’re on this pre-op diet.

Even if you do not have diabetes, you could still have diabetes.

Consume complex carbohydrates

If you notice any of the other symptoms, try adding a bit of complex carbohydrates with these options.

  • Some fat and proteins
  • Fresh fruit with maybe a tablespoon of peanut butter
  • Have a cup of cottage cheese
  • A handful of nuts or string cheese

Here’s what happens

  1. The combination of fresh fruit, fat, and protein slows the release of carbohydrates.
  2. It raises your blood sugar.
  3. It happens slowly so that your body does not release too much insulin.

If your body releases too much insulin, your sugar levels may drop again.

You would go into a yo-yo effect which is prevented by having just a little fat and protein. This slows down the release of carbohydrates.

How do you keep yourself motivated?

Most patients tend to desire their favorite foods just before surgery. They fear that they won’t be able to have them again. Don’t fall into this trap!

When you go down to normal weight, you can start eating everything in moderation.

Don’t binge on food. Stay motivated to go through the weight loss with these helpful tips.

  • Meal planning– This way, you know the exact portions and times of your meals.
  • Hydrate– Avoid dehydration. Water is calorie-free and fills the stomach up.
  • Maintain a food journal– This will help you limit your portions.
  • Keep yourself busy– Stay active and plan your day full of activity to avoid food cravings.

Work with a dietician

Take guidance from a registered bariatric dietitian who will identify your individual requirements and help you get the best results out of the proposed pre-op diet.

He or she can guide you to the best diet for you.

  1. J. Van Wissen, N. Bakker et al. “Pre-operative Methods to Reduce Liver Volume in Bariatric Surgery: A Systematic Review” Obesity Surgery (2016) 26: 251-256
  2. Nutrition Manual.” Cleveland Clinic – Bariatric and Metabolic Institute,
This post addresses
  • Pre-bariatric surgery diet guidelines
  • Liver reduction diet surgery
  • Full liquid diet pre-bariatric surgery
  • Gastric bypass pre-surgery diet plan
  • Pre bariatric surgery diet guidelines
  • RNY pre-op diet
  • Gastric sleeve pre-op diet
  • Why is liver shrink diet necessary?
  • Liver shrinking diet for gastric bypass
  • How to shrink your liver
  • Liver shrinking diet
  • Clear liquid diet before bariatric surgery
  • Diet before gastric bypass
  • Pre-op diet for gastric sleeve
  • Shrink fatty liver
  • What can you have on a liquid diet before surgery?
  • For how long does liver reduction diet continue?

Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *