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Liver Shrinking Diet: What You Need To Know Before Bariatric Surgery

Liver Shrinking Diet: What You Need To Know Before Bariatric Surgery

Bariatric surgery continues to be a tool to help those who are struggling with obesity. Living with excessive weight can take a toll on the body, including damages to vital organs like the liver. Regardless of the surgery choice, it is important to understand the importance of being in “optimal” shape prior to the procedure. The time between the first consultation with the surgeon and surgery day should be used to help prepare the body and mind with the vast changes that will occur post-surgery. This includes the concept of a “liver shrinking diet” before surgery.

What is the liver shrinking diet?

Prior to surgery, patients will need to follow a pre-operative diet, also known as a liver shrinking diet, generally between seven to fourteen days. Bariatric patients will often have an enlarged liver due their excessive weight and poor diet such as foods high in fat and sugar contents.

Foods high in fat and sugar contents can increase risk of an enlarged liver.

By carefully monitoring the patient on a very low calorie diet (VLCD), this will help shrink the liver, as some studies have shown, to minimize risks related to the surgery. Following a restrictive diet with low carbohydrate and fat intake, will help achieve weight loss by forcing the body to use up its stored fat. Our liver and stomach are very close to each other. Since the nature of weight loss surgery is altering the stomach and possibly the intestines, a smaller liver will help the surgeon have easier access to the stomach and minimize any complications.

Diagram of digestive tract

How to shrink your liver

As mentioned earlier, this liver shrinking diet will slightly vary depending on the patient’s situation as far as duration and foods allowed on the diet. Every practice will have a different approach. Some will only allow liquids, primarily meal replacement protein shakes and calorie-free liquids, while others will include protein shakes, appropriate solid foods, and calorie-free liquids.

Despite the differences, the ultimate goal is to lose weight so try not to compare with other patients as each plan is individualized.

Whether it is a seven day or two-week pre-operative liver shrinking diet, the first few days will be the most challenging phase. You will be hungry and probably irritable so be prepared. To make this temporary journey less difficult, follow these guidelines to better prepare for this diet:

  • Once you receive instructions, study it thoroughly and make sure you stock up on all appropriate foods and beverages right away
    • Do NOT procrastinate and prepare ahead of time
  • Try different protein shakes – not all chocolate shakes are made the same (see below for more information)
  • Be familiar with the foods on the list and sample if there are items you have not tried
    • Although some may not be your preference of foods, you do not want to restrict yourself even more than necessary once you start
    • Try to eat/drink ALL items allowed

How do I choose a protein shake?

Protein supplements will be an integral source of energy during the pre-operative diet. When choosing a protein shake, there are few things to look for before purchasing. It is recommended to sample at least a few products to see what you like and dislike. Shop around to see where you will get the best price since you will need a large quantity. Studying and comparing the nutrition facts will be useful. The following is a guideline when choosing a protein supplement:

  • Calories: less than 200 calories
  • Protein: at least 20 – 25 grams
  • Total Carbohydrate: no more than 15 grams
    • Sugar: less than 5 grams
  • Total Fat (including saturated fat): less than 10% Daily Value (DV)
  • Products will have lactose free label for those who are lactose intolerant
  • If choosing a powder form, you can mix with water, skim or 1% milk, unsweetened soy or almond milk
    • Do not add fruit or other food (such as avocado) to shake
List of Frequently Used Meal Replacement Protein Shakes
Ensure® Max Protein
Ensure® High Protein
Premier Protein®
Slim Fast® Advanced Nutrition
Muscle Milk® Genuine Protein Shake
Muscle Milk Light® Protein Shake
GNC Total Lean® Lean Shake 25
GNC Total Lean® Lean Shake Burn
GNC Total Lean® Lean Shake Green (plant based)

What’s in a liver shrinking diet menu?

Patients will be given a pre-operative diet prior to surgery. As mentioned before, each practice will have specific guidelines. However, the overall message is the same. You will be reducing the overall consumption of starchy carbohydrate and fatty foods. Instead, the emphasis will be on lean protein and non-starchy carbohydrate choices including appropriate protein supplements.

Patients will need to avoid caloric beverages such as alcohol, juice, soda, and sweet tea as this will also promote weight loss. Below are lists with recommendations for each major food groups as it will help you make better choices.


Protein can be found in various forms including animal-based and plant-based foods. As you prepare for bariatric surgery, it is recommended to find ways to minimize overall fat intake. Thus, choosing leaner choices is preferable. This list below offers some options.

What is considered one serving of protein?
5 to 6 oz of skim of low-fat yogurt (preferably the “light” version due to its lower sugar content and “Greek” version due to its higher protein content)
1 oz low-fat cheese
1 cup skim or low fat cottage cheese
3 oz tuna packed in water
3 oz of baked, broiled, or grilled lean protein ((skinless chicken breast, beef, pork, fish, tofu, shrimp) – do NOT fry
1 egg (limit to one daily)
1/2 cup cooked beans


Carbohydrate covers a spectrum of a variety of foods. However, the type of carbohydrate that is most concerning is the refined type, commonly referred as the “starchy” carbohydrate, such as pasta, bread, rice, and wraps, as they often dominate the daily diet. To successfully lose the necessary weight and shrink the liver, these types of foods need to be consumed very minimally. If possible, choosing a whole grain, high fiber version is better as it provides more beneficial nutrients.

What is considered one serving of starchy carbohydrate?
1 slice of bread OR 2 slices of light bread
1/2 cup of cooked cereal, pasta, or rice
1 cup ready to eat cereal

Fruits and Vegetables

Fruits and vegetables are natural sources of vitamins and minerals. However, this does not mean we can eat endless amounts of them. Some will have more carbohydrate contents than others, especially fruits and starchy vegetables (ie. potato, corn, carrots). During the liver shrinking diet, it is important to limit fruit intake to 1 serving daily while eating 2 servings of non-starchy vegetables due to its low-calorie content. When preparing vegetables, avoid cooking with fat. Instead, consider steaming, roasting and using lemon juice to add flavor.

Consuming the right amount of fruit and vegetables is important.
What is considered one serving of fruit?
1 “fist-sized” fruit (apple, peaches, nectarine, orange)
1/2 large banana or 1 small banana (6 inches)
1 cup whole grapes
1 cup of whole berries (strawberries, blueberries, blackberries, or raspberries)
1 cup cubed watermelon
1/2 cup dried fruit
1/4 cup 100% fruit juice*
* Fruit juice is not generally recommended as your fruit serving. If you are a diabetic and notice a low sugar level, drink 1/4 cup of juice and continue to monitor.
What is considered one serving of vegetables?
1 cup of raw OR 1/2 cup of cooked leafy green vegetables
1/2 zucchini or squash
1/2 cup broccoli or cauliflower
1/2 bell pepper
1/2 cup sliced cucumbers
1 cup chopped celery
1/2 cup cherry tomato


As a general rule, everyone should be adequately hydrated. However, it is important to know what we are consuming through our fluid intake. Many will be surprised to see how much sugar is consumed just from our beverages. The list below includes suggestions and recommendations with fluid intake.

  • Drink 64 fluid ounces of water daily
  • Start to limit and eliminate all carbonated and caffeinated beverages as you will need to do so post-surgery
  • Avoid all caloric beverages such as juice, soda, alcohol, and sweet iced tea
    • Zero-calorie flavor additives such as Mio® and Crystal Light® and infused water with sliced fruit such as lemon, cucumber, and/or berries are helpful ways to stay adequately hydrated without the calories
Infused water with fresh fruit is a great way to add flavor without calories.

The pre-operative diet will range between 1000 to 1200 calories - significantly less than what most patients consume daily. It is going to be challenging due to the restrictive nature. With help from staff and personal persistence, it is possible. This portion of the journey is usually a good indication of how successful the overall weight loss journey will be after the surgery.  Below are two samples of 1000 calorie dies. Do not hesitate to ask your medical team for help if you have concerns.

Two samples of a 1000 calorie diet

A simple egg avocado toast is a healthier breakfast choice.
Sample A Sample B
Protein shake 1 egg
1/4 avocado
1 slice of light whole grain bread
Snack 6 oz Greek yogurt Protein shake
Lunch Protein shake
Handful of cut up raw non-starchy vegetables (cucumber, bell peppers)
3 oz lean protein
2 handful of green salad
2 tablespoons of light dressing
Snack 1 serving of fruit 1 light string cheese or 1 oz low fat cheese
Dinner 3 oz lean protein
Handful of raw non-starchy vegetable or 1/2 cup of cooked non-starchy vegetable
1/2 cup cooked quinoa or brown rice
3 oz lean protein
1 light whole grain wrap
1 serving of fruit
Snack Protein shake Protein shake

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Eun Jung Park, MS, RD


Eun Jung Park is a registered dietitian with over 10 years experience working in various clinical settings. She graduated from New York University with an Master of Science in Nutrition and Dietetics.

Gintas Antanavicius, MD, FACS, FASMBS

Medical Reviewer

Dr. G is a co-founder of BariBuilder. A US-based expert surgeon with over 10 years of bariatric experience, he regularly publishes research in medical journals like SOARD, Obesity Surgery, etc.