Preparation for bariatric surgery (Liver Shrinkage Diet)

One of the objectives of preparation for bariatric surgery is to reduce the size of the liver in patients with obesity.

It is no secret that all individuals with obesity have so-called non-alcoholic steatohepatitis. The higher the body mass index, the larger the liver size, which may complicate laparoscopic surgery.

What is the goal of the Liver Shrinkage Diet?

During laparoscopic surgery, the liver must be elevated to gain access to the stomach located beneath it. Due to an enlarged fatty liver, it becomes more difficult for the surgeon to visualize and access it.

This may increase the duration of the operation and, consequently, the time the patient spends under general anesthesia.

It may also be dangerous, as the liver is easily injured and may be a source of significant bleeding during surgery.

If this occurs, the surgeon may need to convert to an open procedure instead of performing surgery through small incisions or even cancel the operation and postpone it to a later time.

By following the liver shrinkage diet, the body of a bariatric patient will be forced to utilize stored carbohydrates (glycogen) from the liver.

Glycogen and some amount of water are thereby depleted from the liver, causing it to shrink and become softer, more flexible, and more mobile during surgery.

The liver reduction diet is a low-calorie diet, particularly low in carbohydrates and fats and high in protein.

How long should the Liver Shrinkage Diet be followed?

The duration of the diet is based on the following criteria:

If BMI is less than 50, the diet is followed for up to 14 days; if BMI is greater than 50, the diet is followed for up to 28 days.

What are the options for a liver reduction diet?

All liver shrinkage diets are based on the following principles:

• Approximately 800–1000 kcal.  Less than 100 g of carbohydrates.
• Low fat content.
• High protein content.

OPTION 1 — Milk and yogurt diet

This diet is mainly based on milk, yogurt, and additional fluids.

During this diet, alcohol and all other sources of food should be avoided.

Daily intake:

1.5 liters of skimmed or semi-skimmed milk, or lactose-free or soy milk per day. Milk may be taken hot or cold or flavored with vanilla essence or sugar-free syrups.

2 × 125 g of low-fat plain or natural yogurt or 0% fat yogurt per day. Try to avoid fruit yogurts as they may contain high amounts of sugar and fat. You may add sugar-free syrups or flavorings to plain/natural yogurt to adjust the taste if necessary.

Additionally, a minimum of 2 liters of fluids per day (e.g., water, calorie-free or low- calorie drinks/flavored water, tea/coffee, fruit/herbal teas).

Avoid adding sugar to tea/coffee. As an alternative, sweeteners may be used.

You may use milk from your daily allowance to add to tea or coffee. You will need to take additional vitamins, as this diet is not nutritionally complete. For example: Centrum Advance/Performance.

To maintain electrolyte levels, it is permitted to consume 1 or 2 savory drinks per day. For example: 2 teaspoons made from stock cubes, OXO, Bovril, or consommé dissolved in a large glass of warm water.

Sample meal plan

OPTION 2 — Food-based diet

This diet is based on low-carbohydrate, low-calorie, low-fat, and moderately high-protein meals, along with additional fluid intake throughout the day.

Your meals should follow the format below:

Meal structure

Breakfast:
1 carbohydrate portion
1 dairy portion

Lunch:
NO carbohydrates
2 protein portions
2 vegetable portions

Dinner:
2 carbohydrate portions
1 protein portion
1 vegetable portion
1 dairy portion

Snacks:
2 portions of fruit per day — can be consumed at any time.

What is a portion?

Sample meal plan

Foods to avoid:

It is important to avoid any foods high in sugar and fat, including:

• Sweets: chocolate/cakes, jelly, ice cream.
• Sugary drinks, including juices/soft drinks.
• Alcohol.
• Added sugar in hot drinks/foods (sweeteners may be used as an alternative).
• Chips.
• Fried foods/takeaway food.
• Cream-based or ready-made pasta dishes or sauces (use canned tomatoes in cooking, e.g., in sauces/stews/casseroles).
• Breaded meat/fish products (choose fresh/lean options).

Fluid intake:

A minimum of 2 liters of fluids, including:

• Water.
• Tea/coffee (you may add milk from your daily dairy allowance).
• Sugar-free squash/flavored water.

You will need to start taking multivitamin and mineral supplements once daily, as this diet is not nutritionally complete. For example: Centrum Advance/Performance.

Additional information

Patients may experience headaches or “mild dizziness” after starting the liver shrinkage diet. This is quite common and will pass within the first few days.

Constipation may become an issue while following this diet, as it contains very little fiber. Bariatric patients may need to take 1–2 sachets of Duphalac daily or any other laxatives in tablet or powder form to prevent this.

Patients are expected to experience some weight loss during the liver shrinkage diet. Therefore, female patients should be aware that changes in the menstrual cycle may occur during this period. In addition, women with polycystic ovary syndrome may ovulate and become fertile during the liver shrinkage diet, so it is important to use contraception.

Please note that bariatric patients must stop eating 6 hours before surgery and stop drinking water 2 hours before surgery.