Once a rare disorder, nonalcoholic fatty liver disease, or NAFLD, has now become all too common. It's estimated to affect about 25% of the population in most Western countries, and as many as 1 billion people worldwide. Even children are now being affected.
Although NAFLD can have dire consequences, it can potentially be improved - and in some cases even reversed - with a keto or low-carb approach. In this guide, we'll tell you how.
Key takeaways
Keto diets are potentially beneficial for people with NAFLD because they can:
- Reduce liver fat
- Decrease insulin levels
- Help reverse the disease process
- Suppress appetite, promote weight loss, and improve heart health markers
- Provide a healthy, satisfying way of eating that can be maintained long term
What is nonalcoholic fatty liver disease (NAFLD)?
In nonalcoholic fatty liver disease (NAFLD), too much fat is stored in the liver. Although everyone has a little fat in their liver, fat makes up more than 5% of the liver in people with fatty liver disease.
In the past, fatty liver was seen almost exclusively in people who regularly consumed large amounts of alcohol, but today factors other than alcohol are the leading cause, hence the name NAFLD. One of the criteria for NAFLD is having a fatty liver but averaging less than two alcoholic beverages (20-30 grams of alcohol) per day.
Nonalcoholic hepatic steatosis, known more simply as nonalcoholic fatty liver, is the earliest stage of NAFLD. In some people, the disease remains at this stage and never progresses. Although they experience metabolic issues related to excess liver fat, they don't sustain significant liver damage.
But in 25-30% of all cases, fatty liver progresses to a more serious condition known as non-alcoholic steatohepatitis (NASH), in which the liver cells become inflamed and injured. When the liver attempts to repair these damaged cells, scar tissue forms, resulting in a condition called fibrosis.
Eventually, about 20% of NASH cases may progress to cirrhosis - end-stage, irreversible liver disease that usually results in liver failure.
While only a portion of all NAFLD cases progress to NASH and then cirrhosis, non-progressing NAFLD can still be a health problem. NAFLD has been linked to increased risk of heart disease and type 2 diabetes.
Unfortunately, many people aren't aware they have NAFLD because symptoms like abdominal swelling, loss of appetite, and jaundice usually don't develop until the disease is well advanced.
What causes NAFLD?
Several things can contribute to the development of NAFLD. These include:
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Too many refined carbs: Consuming more carbohydrates than your body is able to handle can drive liver fat storage via a process known as de novo lipogenesis (literally "making new fat"). This typically happens when both carb and calorie intake are high.
In one study, when overweight adults ate 1,000 extra calories as refined carbs, they experienced a 27% increase in liver fat after just three weeks. - Too much sugar: When it comes to excess carbs, sweets and sugar-sweetened beverages may be especially problematic. These items are high in fructose, which has been shown to increase liver fat when consumed in large amounts. Some researchers believe that high fructose intake is a major contributor to NAFLD.
Risk factors for NAFLD
Not everyone who consumes a lot of refined carbs and gets little exercise will end up developing NAFLD. So who is most likely to get it?
Here are some things that increase the likelihood of developing NAFLD:
- Insulin resistance: People with insulin-resistant conditions like type 2 diabetes and metabolic syndrome are at higher risk for NAFLD. Although the exact mechanism isn't completely understood, insulin resistance and high insulin levels are known to drive excessive storage of liver fat.
How to know if you have NAFLD
NAFLD is diagnosed by lab tests, a liver ultrasound or a CT scan, and sometimes a liver biopsy. In blood tests, in addition to high triglycerides and insulin levels, certain liver enzymes are elevated, especially GGT and ALT. An ultrasound or CT scan will show excess fat or other changes in the liver.
Using a formula that calculates the combined effects of triglycerides, GGT, waist size and BMI, the Fatty Liver Index has been shown to help predict the likelihood that someone has NAFLD. However, in at least one study, waist size alone was found to similarly predict this risk.
If you think you may have NAFLD, follow up with your doctor for further testing.
Why a keto or low-carb diet can improve NAFLD
Historically, because many people with NAFLD are overweight, dietary recommendations for the condition have been primarily low-calorie or low-fat diets. However, besides being difficult to stick with long term, these diets may do little to address the root causes of NAFLD.
Recently, keto eating has been shown to improve NAFLD in a number of ways.
Keto and low-carb diets can help people with NAFLD because they:
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Decrease liver fat: Since eating too many carbs can increase liver fat storage, it makes sense that cutting back on carbs can have the opposite effect. And studies have confirmed that this is exactly what occurs.
In an eight-week randomized controlled trial (RCT) of 106 people with NAFLD, people who ate a low-carb diet had greater reductions in liver fat and less abdominal fat than those who ate a low-fat diet. Several smaller trials have also shown a decrease in liver fat with a low-carb approach. -
Reduce insulin levels and insulin resistance: A very-low-carb diet can dramatically improve insulin sensitivity in people with NAFLD - and often very quickly.
In one study, people with NAFLD who ate a keto diet for six days had a 58%decrease in insulin resistance and a 53% decrease in insulin levels. According to the researchers, the lower insulin levels allowed liver fat to be broken down and converted into ketones. -
May help reverse the disease process: Several small studies have shown that in addition to preventing the progression of NAFLD, keto eating may actually reverse the disease.
In a 12-week study of people with metabolic syndrome and NAFLD who followed a Spanish Mediterranean ketogenic diet, 13 of 14 people had a decrease in liver fat levels, and three had a complete resolution of NAFLD. In another small trial, patients with NAFLD ate a diet that limited carbs to 20 grams per day for six months. By the end of the study, fatty liver, inflammation, and fibrosis had improved in four of the five patients. And in the analysis of one-year data from Virta Health's large ongoing study in people with type 2 diabetes, most participants with NAFLD who followed a very-low-carb diet had reductions in liver fat and fibrosis scores. - Suppress appetite, promote abdominal fat loss, and improve heart health markers: Ketogenic diets have been shown to help reduce appetite in several studies, including a meta-analysis of RCTs, which is considered the strongest, highest-quality evidence. In several trials, people with NAFLD who followed a keto or low-carb diet ended up eating less and losing abdominal fatwithout intentionally restricting calories. Other benefits of low-carb eating include reductions in heart disease risks factors, such as lower blood triglycerides, blood sugar, and blood pressure.
Getting started with low carb or keto for NAFLD
After getting the OK from your doctor, you can learn the basics of low-carb eating in our keto and low-carb diet guides.
Although a very-low-carb approach seems to produce the most dramatic reduction in liver fat, if you'd rather reduce carbs more gradually, read Eating better: Six steps down the carb mountain to get started.
In addition to paying attention to carb intake, make sure to get enough protein. Higher protein intake has been found to reduce liver fat in people with NAFLD, as well as those with type 2 diabetes. Use our target protein ranges chart to figure out how much you need.
Other lifestyle changes that may improve NAFLD
In addition to eating low carb, a few other changes might also be helpful:
Summary
Fatty liver disease occurs due to a combination of lifestyle and genetic factors. If allowed to progress from simple fatty liver, it can sometimes lead to more serious liver disease.
The good news is that a low-carb or keto diet can lead to a dramatic loss of liver fat and may potentially reverse the disease. The time to start is now, so you can begin living your healthiest, best life.
