Fatty liver disease and keto: 5 things to know
Although NAFLD can have dire consequences, it can potentially be improved — and in some cases even reversed — with a low-carb or keto approach. In this guide, we’ll tell you how.
Low-carb or 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
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. 3 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 criterion for NAFLD is having a fatty liver but averaging less than two alcoholic beverages (20-30 grams of alcohol) per day.4 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.5
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 an increased risk of heart disease and type 2 diabetes.6
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 significantly advanced.
What causes NAFLD?
Several things can contribute to the development of NAFLD. These include:
- Excess energy intake: Eating more calories than needed may lead to excess fat accumulation in the liver — and research suggests this can happen no matter what type of food is over consumed.7
- 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”).8 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.9
- 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.10 Some researchers believe that high fructose intake is a major contributor to NAFLD.11
- Sedentary lifestyle: Observational research suggests that spending too much time sitting rather than moving may promote excess liver fat storage.12 However, this is hard to differentiate from other potential contributing lifestyle factors.
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 promote excessive storage of liver fat.13
- Carrying too much weight around the middle: Because it’s so strongly linked to high insulin levels, large waist size places people at increased risk for NAFLD, even if their BMI is in the “normal” range.14
- Genetics: Some people are more likely to develop NAFLD because they’ve inherited certain gene variants that increase their risk for the disease. However, further research in this area is needed.15
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. With blood testing, certain liver enzymes are elevated, especially GGT, ALT, and AST. Triglycerides and insulin levels also tend to be high. An ultrasound or CT scan will typically show excess fat 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.16
If you already have a diagnosis of NAFLD and want to know more about how far it has progressed, some gastroenterologists are using a special kind of ultrasound called FibroScan. This is less invasive than liver biopsy and can be used to determine whether fibrosis has occurred and to what extent. It can also be used to track progression or regression of NAFLD over time.17
If you think you may have NAFLD, follow up with your doctor for further testing.
Why a low-carb or keto diet can improve NAFLD
Because many people with NAFLD are overweight, they often receive recommendations to eat low-calorie or low-fat diets. However, that may not be the best choice for many people. While many diets that lead to weight loss can improve fatty liver, evidence suggests low-carb diets may be more effective than low-fat.18 The other important consideration is finding a diet you are most likely to stick with long-term.
Low-carb and keto diets can help people with NAFLD because they:
- 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, those who ate a low-carb diet had greater reductions in liver fat and less abdominal fat than those who ate a low-fat diet.19 Several smaller trials have also shown a decrease in liver fat with a low-carb approach.20 And one RCT reported a keto diet and a 5:2 fasting regimen were superior to standard advice from a liver specialist in reducing liver steatosis.21
- 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.22 Another study reported almost 50% improvement in liver function tests and markers of insulin resistance in patients with NAFLD who followed a low-carb diet.23
- May help reverse the disease process: Several small studies have shown that in addition to preventing the progression of NAFLD, low-carb 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.24 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.25 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.26
- 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.27 In several trials, people with NAFLD who followed a keto or low-carb diet ended up eating less and losing abdominal fat without intentionally restricting calories.28 Other benefits of low-carb eating include reductions in heart disease risks factors, such as lower blood triglycerides, blood sugar, and blood pressure.29
Getting started with low carb or keto for NAFLD
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.30 Use our target protein ranges chart to figure out how much you need.
Other lifestyle changes that may improve NAFLD
Besides eating low carb, a few other changes might also be helpful:
- Exercise regularly: Being more physically active can help reduce insulin resistance and liver fat. Which type of exercise is best? In a review of 12 trials, performing either aerobic exercise or resistance training for 40-45 minutes three times a week was found to be beneficial for NAFLD.31 So choose the type of exercise you prefer and that feels sustainable. Or better yet, aim for a combination of both, if you can.
- Include fatty fish in your diet: Try to eat salmon, sardines, mackerel, or anchovies at least twice a week. These fish are high in omega-3 fats, which have been shown to reduce liver fat, GGT, and triglycerides in people with NAFLD.32
- Consider turmeric or curcumin: You may know turmeric as the bright-yellow, pungent spice used in Indian and Asian curries and other dishes. Studies suggest that turmeric or its active component curcumin may help lower liver enzymes in those with NAFLD.33
Curcumin has also been shown to produce slight weight loss and reduce waist size in people who are overweight or have metabolic syndrome.34
Try increasing the amount of turmeric in curries and other recipes that call for it, like our Keto coconut curry chicken or Pork tenderloin with curry sauce. Another option is to take a supplement containing 500 mg of curcumin.
Note: If you take blood thinners, do not take curcumin or turmeric before speaking with your doctor or pharmacist.
Medications for NAFLD
While diet and exercise are the first and most important interventions for NAFLD, there are some pharmacologic options as well.
- Vitamin E: What is the rationale for using vitamin E to treat fatty liver? Because oxidative stress plays a role in NAFLD, a powerful antioxidant like vitamin E has the potential to modify the underlying disease process. Although research over the years has been mixed about how helpful it is, a recent meta-analysis of RCTs suggests that high-dose vitamin E does improve both liver enzymes and the features of NAFLD seen on liver biopsy, at least in adults.35 Why do we consider vitamin E a medication and not simply a supplement? When used at the high doses necessary for treating NAFLD, vitamin E carries many risks that merit careful consideration: hemorrhagic stroke, prostate cancer, and all-cause mortality.36
- Pioglitazone: This diabetes drug has also been extensively studied as a treatment for NAFLD, and has been shown to improve disease activity, reduce the progression to liver fibrosis, and also improve multiple cardiometabolic risk factors.37 If you have fatty liver and type 2 diabetes that isn’t well-controlled on your current diabetic regimen, pioglitazone may be a reasonable option that can do double-duty. As with any other medication, talk to your doctor about the potential side effects, such as weight gain.
- GLP-1 receptor agonists: This class of diabetes medication has been in the news lately due to semaglutide’s potency as a weight loss drug, but the class as a whole has also been studied for NAFLD. GLP-1 receptor agonists have been shown to improve liver enzymes, reduce fatty infiltration of liver cells, and reverse liver fibrosis.38 Because the medications in this class lower blood sugar and cause weight loss, they may be a reasonable choice as add-on therapy for people with type 2 diabetes and fatty liver.
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.
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Fatty liver disease and keto: 5 things to know - the evidence
The guide contains scientific references. You can find these in the notes throughout the text, and click the links to read the peer-reviewed scientific papers. When appropriate we include a grading of the strength of the evidence, with a link to our policy on this. Our evidence-based guides are updated at least once per year to reflect and reference the latest science on the topic.
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PLoS One 2015: The Prevalence of Non-Alcoholic Fatty Liver Disease in Children and Adolescents: A Systematic Review and Meta-Analysis[meta-analysis and review of population and intervention studies; moderate evidence]
American Journal of Clinical Nutrition 2003: Hepatic de novo lipogenesis in normoinsulinemic and hyperinsulinemic subjects consuming high-fat, low-carbohydrate and low-fat, high-carbohydrate isoenergetic diets [nonrandomized study, weak evidence] ↩
The American Journal of Clinical Nutrition 2012: Effect of short-term carbohydrate overfeeding and long-term weight loss on liver fat in overweight humans [non-controlled study; weak evidence] ↩
In one trial, overweight people were randomly assigned to consume 1 liter (about 32 ounces) of either sugar-sweetened beverages, milk, diet soda, or water every day for six months. By the end of the trial, liver fat had increased significantly more in the sugar-sweetened beverages group compared to the other groups:
The American Journal of Clinical Nutrition 2012: Sucrose-sweetened beverages increase fat storage in the liver, muscle, and visceral fat depot: A 6-mo randomized intervention study [randomized trial; moderate evidence]
Similar results were seen in a shorter trial in normal-weight men:
Hepatobiliary Surgery and Nutrition 2015: Carbohydrate intake and nonalcoholic fatty liver disease: fructose as a weapon of mass destruction [overview article; ungraded]
Nutrients 2017: Fructose consumption, lipogenesis, and non-alcoholic fatty liver disease [overview article; ungraded] ↩
Hepatology 2020: Inadequate physical activity and sedentary behavior are independent predictors of nonalcoholic fatty liver disease [observational study; very weak evidence]
Journal of Applied Physiology 2011: Does physical inactivity cause nonalcoholic fatty liver disease? [overview article; ungraded] ↩
The Lancet. Gastroenterology and Hepatology 2020: FibroScan-AST (FAST) score for the non-invasive identification of patients with non-alcoholic steatohepatitis with significant activity and fibrosis: a prospective derivation and global validation study[non-controlled study; weak evidence] ↩
In fact, in one intervention trial, a low-fat diet led to some benefit for NAFLD, but not as much as a low-carb or Mediterranean diet:
Hepatology Research 2018: Comparison of efficacy of low-carbohydrate and low-fat diet education programs in non-alcoholic fatty liver disease: A randomized controlled study [randomized trial; moderate evidence] ↩
Journal of Hepatology 2019: The beneficial effects of Mediterranean diet over low-fat diet may be mediated by decreasing hepatic fat content [randomized trial; moderate evidence]
The American Journal of Clinical Nutrition 2011: Short-term weight loss and hepatic triglyceride reduction: Evidence of a metabolic advantage with dietary carbohydrate restriction [non-controlled study; weak evidence]
Cell Metabolism 2018: An integrated understanding of the rapid metabolic benefits of a carbohydrate-restricted diet on hepatic steatosis in humans[non-controlled study; weak evidence] ↩
Proceedings of the National Academy of Sciences of the United States of America 2020: Effect of a ketogenic diet on hepatic steatosis and hepatic mitochondrial metabolism in nonalcoholic fatty liver disease [non-controlled study; weak evidence] ↩
Current Developments in Nutrition 2021: Effects of a low carbohydrate diet on patients with metabolic syndrome complicated by non-alcoholic fatty liver Ddisease (NAFLD) [non-controlled study; weak evidence] ↩
BMJ Open 2019: Post hoc analyses of surrogate markers of non-alcoholic fatty liver disease (NAFLD) and liver fibrosis in patients with type 2 diabetes in a digitally supported continuous care intervention: an open-label, non-randomised controlled study [non-controlled study; weak evidence] ↩
Hepatology Research 2018: Comparison of efficacy of low-carbohydrate and low-fat diet education programs in non-alcoholic fatty liver disease: A randomized controlled study [randomized trial; moderate evidence]
The American Journal of Clinical Nutrition 2011: Short-term weight loss and hepatic triglyceride reduction: evidence of a metabolic advantage with dietary carbohydrate restriction [non-controlled study; weak evidence]
Journal of Medicinal Food 2011: The effect of the Spanish Ketogenic Mediterranean diet on nonalcoholic fatty liver disease: A pilot study [non-controlled study; weak evidence] ↩
All participants in the Spanish Mediterranean diet trial had such impressive improvements in these health markers that by the end of the study, they no longer met the criteria for metabolic syndrome:
Journal of Medicinal Food 2011: The effect of the Spanish Ketogenic Mediterranean diet on nonalcoholic fatty liver disease: A pilot study [non-controlled study; weak evidence]
Similar improvements have been seen in other trials:
Journal of Hepatology 2019: The beneficial effects of Mediterranean diet over low-fat diet may be mediated by decreasing hepatic fat content [randomized trial; moderate evidence]
Cell Metabolism 2018: An integrated understanding of the rapid metabolic benefits of a carbohydrate-restricted diet on hepatic steatosis in humans [non-controlled study; weak evidence] ↩
Nutrición Hospitalaria 2014: Hypocaloric high-protein diet improves clinical and biochemical markers in patients with nonalcoholic fatty liver disease (NAFLD) [non-controlled study; weak evidence]
Cell Metabolism 2018: An integrated understanding of the rapid metabolic benefits of a carbohydrate-restricted diet on hepatic steatosis in humans [non-controlled study; weak evidence]
Diabetologia 2019: A carbohydrate-reduced high-protein diet improves HbA1c and liver fat content in weight stable participants with type 2 diabetes: a randomised controlled trial. [randomized controlled trial; moderate evidence]
Gastroenterology 2017: Isocaloric diets high in animal or plant protein reduce liver fat and inflammation in individuals with type 2 diabetes [randomized controlled trial; moderate evidence] ↩
Integrative Medicine Research 2019: Efficacy of curcumin/turmeric on liver enzymes in patients with non-alcoholic fatty liver disease: A systematic review of randomized controlled trials [systematic review of randomized trials; strong evidence]
Phytotherapy Research 2019: Does turmeric/curcumin supplementation improve serum alanine aminotransferase and aspartate aminotransferase levels in patients with nonalcoholic fatty liver disease? A systematic review and meta-analysis of randomized controlled trials [systematic review of randomized trials; strong evidence]
Frontiers in Pharmacology 2019: The effects of curcumin on weight loss among patients with metabolic syndrome and related disorders: a systematic review and meta-analysis of randomized controlled trials [strong evidence]
Critical Reviews in Food Science & Nutrition 2018: The effects of curcumin supplementation on body weight, body mass index and waist circumference: a systematic review and dose-response meta-analysis of randomized controlled trials [strong evidence] ↩
While the benefit of vitamin E in adults appears fairly clear in this meta-analysis, the data cannot prove that it is beneficial for children with NAFLD.
Postgraduate Medical Journal 2019: Effect of vitamin E in non-alcoholic fatty liver disease: a systematic review and meta-analysis of randomised controlled trials [systematic review of randomized trials; strong evidence] ↩
Diabetologia 2012: Impact of current treatments on liver disease, glucose metabolism and cardiovascular risk in non-alcoholic fatty liver disease (NAFLD): a systematic review and meta-analysis of randomised trials [systematic review of randomized trials; strong evidence] ↩
Endocrinology, Diabetes, and Metabolism 2020: Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) for the management of nonalcoholic fatty liver disease (NAFLD): A systematic review[systematic review of clinical trials; moderate evidence] ↩