How to shrink your liver before bariatric surgery

Written by Ciara House, MS, RD, LDN and medically reviewed by Dr. Stephen Boyce, MD
How to shrink your liver before bariatric surgery Bari Life

Your biggest responsibility prior to having bariatric surgery is to follow a strict pre op diet to lose weight quickly and reduce the size of your liver to make the surgery easier for your surgeon. But how can you tell if your liver is shrinking?

I’m sure you’ve been told you need to follow a special pre bariatric surgery diet, but you may not know why this is actually a critical step that you must take seriously as a patient.

One obvious reason is that your surgeon wants you to lose as much weight as quickly and safely as possible prior to surgery. There is compelling data to suggest that the higher your Body Mass Index (BMI), the greater the risk for complications to occur during your surgery.

This study found that the odds of postoperative complications increased by 2% with every point increase in BMI.

However, there is a second reason for the pre op diet directive: to shrink your liver before your bariatric surgery.

Why do you want your liver to shrink before bariatric surgery?

All bariatric surgical procedures deal with the stomach in some capacity. As it turns out, the liver and stomach are in close proximity to one another. In fact, as you lie on the operating table the liver actually sits on top of the stomach.

How to shrink your liver before bariatric surgery Bari Life

This means that your surgeon has to lift and move around the liver to get to the stomach so she/he can perform the operation. So it stands to reason that the bigger your liver is on surgery day, the more difficult it is for the surgeon to perform the operation…

And the more difficult it is for the surgeon the higher the risk for complications…

You put yourself at higher risk to deal with other things after surgery instead of being able to focus on losing weight and recovering from the surgery by not complying with your pre bariatric surgery diet.

What causes the liver to shrink?

In some cases, liver shrinkage is a bad thing and can be associated with diseases like Liver cirrhosis, Drug-induced liver diseases and hepatitis.

Fortunately, this isn’t the type of liver shrinkage that is intended before bariatric surgery, obviously. But there are a couple of primary drivers that cause the liver to shrink before bariatric surgery.

Glycogen and Water Stored in the Liver

The liver is a storage center for glycogen, a form of energy that comes from foods we eat, mostly carbohydrates. The more carbohydrates we consume the more glycogen is stored in the liver and muscles, which adds weight and bulk to the liver. But it doesn’t stop there.

While the glycogen stores do add weight and bulk, it doesn’t get stored all by itself. Glycogen and water are stored in the liver and in muscles at a 1:3 ratio – meaning that for every 1 gram of glycogen stored 3 grams of water is stored with it which adds up to some serious volume in the liver.

How to shrink your liver before bariatric surgery Bari Life

Since most of the carbohydrates we eat are converted into glycogen, the more carbohydrates we eat, the more glycogen (and water) is stored.

On the flip side, the fewer carbohydrates the less glycogen (and water) stored. In fact, our bodies will actually use that stored glycogen for energy, resulting in an outflow of glycogen and water, shrinking the liver.

Not-so-coincidentally, when you follow a very strict diet that is low in starch and sugars your body loses its glycogen stores and water resulting in your liver shrinking.

[Quick Note: This is what makes Ketogenic diets so popular – you lose a ton of weight in a short period of time because you shed glycogen and water from your liver and muscles. This makes the number drop on the scale quickly, but it’s not 100% body fat, it’s mostly water weight that comes back when eating returns to normal.]

This is exactly why bariatric surgeons and dietitians prescribe a Very Low-Calorie Diet (VLCD) which is also low in carbohydrates.

Fat Stored in the Liver

Not all body fat is stored where you can see it, it is also stored in our internal organs, including the liver.

As you follow your 800 calorie Very Low-Calorie (VLCD) pre op diet you will lose body fat from everywhere, including the liver. So the more consistently you can stick to your pre op diet the more weight you will lose, more your liver will shrink and the happier your surgeon will be on surgery day.

How do you make your liver shrink for bariatric surgery?

The good news is that intentional shrinkage of the liver can be controlled by consistently following a low-carbohydrate, low-calorie diet.

Most bariatric surgery centers will advise new patients to follow an 800 calorie, Very Low Calorie Diet (VLCD).

How to shrink your liver before bariatric surgery Bari Life

These diets are high protein, low carbohydrate and low fat. As you consume fewer carbohydrates your body begins to use glycogen stores from your muscles and liver instead of storing them from new carbohydrates.

Over time, the volume of glycogen and water reduces in the liver, and the size of the liver decreases and you lose quite a bit of weight very quickly.

If you “cheat” during your VLCD your liver will not shrink properly and your surgeon and her/his surgical team will know at first glance of your liver.

How can you tell if your liver is shrinking?

Unfortunately, you can’t tell if your liver has decreased in size by feeling your stomach or anything like that.

The only way to see is if you have a diagnostic test like a CT scan, which isn’t very practical for pre bariatric surgery planning and consultations.

Most surgeons will tell you that if you’re following the prescribed pre bariatric surgery diet AND you’re losing weight, your liver is shrinking as it should be.

How to shrink your liver before bariatric surgery Bari Life

You must trust the pre surgery diet, follow it without little-to-no deviation for the short time that you’re required to do so and you’ll be prepped and ready for surgery. At most your pre bariatric surgery diet will last 4 weeks. You can do ANYTHING for 4 weeks, right?

What happens if my liver doesn’t shrink before bariatric surgery?

Surgeons care about positive and safe outcomes. There is certainly a possibility that the surgeon will not perform the surgery if you do not prepare yourself for the surgery day as required.

Canceled/Postponed Surgery

If there is a higher chance for complications, it can be seen as a liability and you’ll be postponed even further. So it’s best to follow a strict pre bariatric surgery diet to a “T.”

Damage to the liver

Large and fattier livers tend to have a different texture than a more typical liver condition. This can become a problem as your surgical team attempts to lift and position your liver, the instruments can actually cut into the liver and cause liver lacerations.

If this happens there is a good chance of bleeding, bile leakage and future infection. This is NOT something you want to experience.

It’s a short sprint of a diet, no more than 4 weeks, so just find a plan and stick to it. Your future self will thank you for it.

Pre Bariatric Surgery Diet Bundles

How to shrink your liver before bariatric surgery Bari Life

By rapidly losing weight and shrinking the liver prior to surgery the risk of complications is reduced significantly. It also helps to prepare you for the necessary 4 Phase Diet that is prescribed immediately after surgery.

Putting together your own Pre-Op Bariatric Diet can be difficult, that’s why we made the Bari Life Pre-Op Diet.

And to make your pre op diet even easier to follow, we’ve bundled together our best-selling items that fit perfectly for your specific needs.

All you have to do is follow the instructions that come with the bundles and you’re sure to lose weight and shrink your liver to be prepared for your bariatric surgery.

Learn more about the pre bariatric surgery diet bundles here.

The Bottom Line on How to Tell if Your Liver is Shrinking

There’s no easy physical exam that you can have that will tell you if your liver is shrinking or not while you’re on your pre bariatric surgery diet. The good news is that there are two primary indicators that will tell you if your liver is shrinking.

  1. Have you been losing weight?
  2. Have you been following your pre bariatric surgery diet consistently without cheating?

If you can say “yes” to both of these questions your liver is shrinking and you’re doing well to prepare for your bariatric surgery. If you cannot say yes to both, then you need to get back on track with your pre bariatric surgery diet to avoid your surgery being cancelled, or worse, end up with complications during and after the surgery.

If you follow your diet like your surgeon and dietitian instruct you, you’ll be fine. Stay calm and take it one day at a time and enjoy the process leading up to your surgery. You’re in this for the long-term so these short few weeks are well worth the sacrifice to ensure a positive bariatric surgery outcome.


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