Different dietary interventions and eating plans for metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH) have gained a lot of interest among researchers. One example of an eating plan is the low-carbohydrate diet, which involves reducing the amount of carbs you eat each day, especially those from grains. Studies on low-carb diets for MASLD have shown mixed results. Learn more about the effects of these diets and factors to consider if you have MASH or MASLD.
Understanding MASLD and MASH
You may have heard of these liver conditions referred to by a different name. Metabolic dysfunction-associated steatotic liver disease was previously called “nonalcoholic fatty liver disease (NAFLD)” and metabolic dysfunction-associated steatohepatitis used to be called “nonalcoholic steatohepatitis (NASH).”
MASLD occurs when your body stores excess fat in your liver. This buildup of fat can lead to inflammation of the liver, which, over time, can cause liver damage and may lead to fibrosis (scarring of the liver). If left untreated, this can lead to cirrhosis (severe scarring) or even liver failure. Therefore, preventing, reducing, or eliminating is important for people living with MASLD and MASH (an advanced form of MASLD).
Lifestyle changes, such as maintaining a healthy, balanced diet, can help reduce or even get rid of liver inflammation caused by MASH. Doctors suggest weight loss as a treatment for MASLD and MASH because it helps address the health conditions that contribute to fatty liver disease. Some risk factors associated with MASH include:
- Having overweight or obesity
- Having high cholesterol or blood pressure
- Having high blood sugar
- Being insulin resistant
- Living with diabetes
- Living with metabolic syndrome (a group of risk factors for cardiovascular disease)
Doctors note that some of the best ways to lose weight, in addition to exercise, are to eat a healthy diet and reduce the number of calories you eat in a day. Could this be achieved with a low-carb diet?
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The Role of Low-Carb Diets
Studies show different effects of low-carb diets on MASLD, making it unclear how valuable they are compared to other eating plans. Some researchers think the mixed results may be due to the different definitions of a low-carb diet, each with different rules on the amount and type of carbohydrate intake.
Some studies support the idea that restricting carbs could help reduce liver inflammation, fat, and enzyme levels in people with MASLD. Other studies have shown a low-carb diet is associated with improvements in some parts of liver health, like liver fat content, but not others.
For example, one study showed that consuming less than 50 percent of total calories from carbs was associated with reduced liver fat but not liver enzymes, which are higher in people with MASH.
Although some research has shown the benefits of following a low-carb diet for MASLD, low-carbohydrate eating plans might not be more effective than low-calorie diets for managing MASLD and MASH.
One study found that people on a low-carb, high-fat diet (like the ketogenic diet) had a reduced amount of liver fat compared to those on a generally healthy diet. In this study, the low-carb, high-fat diet meant only 5 percent to 10 percent of the total daily calories came from carbs. For reference, the Dietary Guidelines for Americans recommend that 45 percent to 65 percent of daily calories should come from carbs. However, the study results showed no difference between the low-carb, high-fat diet and a specific type of calorie-restricted diet that included fasting.
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Another study showed no significant association between a low-carb diet and the risk of MASLD.
More research is needed to better understand if and how low-carb diets may help with MASLD and MASH, as well as what kind of carb restriction may lead to improvement in this condition, especially because the term “low-carb diet” can mean many different things.
Low carbohydrate diet definition is very inconsistent, but according to Seidelmann et al. new study (38) optimal proportion of carbohydrate for a healthy diet is 50-55%.
The Importance of Carb Quality
The quality of carbs, fat, and protein and where they come from are important factors when comparing different diets for MASLD. For example, one study noted that foods made of plant protein, unsaturated fat, and high-quality carbs (such as whole grains) are associated with a lower risk of MASLD. The researchers noted that if you don’t take into account the quality or source of the carbs and fats, there isn’t a significant association between a low-fat or low-carb diet and reduced risk of MASLD.
Calorie Restriction vs. Carb Restriction
Some research has suggested that eating fewer calories may be more important than just practicing carbohydrate restriction. For instance, one study concluded that all diets that restrict calories are effective in reducing body weight, liver enzyme levels, and liver fat in people with MASLD and MASH. In this study, the low-fat and low-carb diets, both low in calories, were associated with similar reductions in body weight, liver fat, and liver enzymes.
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A different study found no significant difference between a low-carb diet and a low-fat diet in affecting liver fat levels in people with MASLD. The researchers concluded that if the calorie intake is the same, a low-carb diet may not be any more helpful for MASLD than a low-calorie diet. This finding has led some researchers to emphasize a low-calorie diet over a low-carb diet.
Furthermore, scientists found that calorie restriction was associated with improvements in MASLD, no matter whether the calories came from fat, carbs, or protein (the three macronutrients). In other words, reducing the overall number of calories may be more helpful than reducing any one type of macronutrient, such as carbs. However, it’s still important to focus on the type of calories you consume. It’s best for your liver and overall well-being to have more natural and wholesome foods, rather than those that are highly processed.
Potential Risks of Low-Carb Diets
Although low-carb diets are popular and may advertise promising results, they may have risks. Researchers have noted that low-carb diets may not have enough important nutrients like fiber, vitamins, and calcium if they’re followed long term.
For example, a low-carb diet may not include enough fiber-rich whole-grain foods, such as brown rice or whole wheat bread because they are high in carbs. Fiber is important for liver health, and a lack of fiber in low-carb diets can lead to constipation.
A low-carb diet may also lead to other health issues. One study found that although a low-carb, high-fat diet reduced liver fat levels, it led to higher levels of LDL cholesterol, which has been linked to cardiovascular disease. Low-carb diets have also been linked to osteoporosis and osteopenia.
The Keto Diet and Fatty Liver Disease
More research shows that the keto diet can not only assist in weight loss, but that it can also help prevent Fatty Liver Disease and reverse fatty liver damage. But before we discuss why a keto diet can help with Fatty Liver Disease, let’s review what it is. The ketogenic diet consists of a very low carbohydrate diet, typically between 5-10 percent of total calories for the day.
The most common type of keto diet consists of a high fat intake and low carbohydrate intake diet with an unrestricted total calorie intake. Tracking macronutrient levels are key to the keto diet.
The goal of the keto diet is to achieve ketosis, or ketogenesis. Ketogenesis happens when your body uses fat instead of carbohydrates for energy.
During ketogenesis, ketone bodies are formed - these are water-soluble molecules produced by the liver from fatty acids. Ketone bodies assist with weight loss thanks to their ability to induce satiety - or the sensation of fullness. This can lead to eating smaller portions without feeling hungry.
Additional benefits of the keto diet include a reduction in triglycerides, abdominal fat, and risk for Metabolic Syndrome. As you work towards ketosis by reducing your carb intake, you will eat more foods that have a low-glycemic index like vegetables and certain fruits. These foods have less of an impact on your blood glucose levels than high-glycemic foods. A diet rich in low-glycemic index foods helps reduce insulin resistance and keep a steady blood sugar level.
How Keto Helps Fatty Liver
Keto doesn’t only offer weight loss and insulin level improvement to combat fatty liver. The diet also reduces lipogenesis.
Lipogenesis is the process of converting carbohydrates into fatty acids, thus turning them into fat. This fat tends to end up in tissue around the midsection and the liver. By reducing the fat conversion process, less fat may be stored in the liver.
Not only does a low-carb diet reduce insulin levels and lipogenesis - it can increase the rate fatty acids are broken down, or their oxidation rate. Reducing oxidative stress helps reduce inflammation and irritation in the liver.
Research on Keto and Fatty Liver
It may seem counterintuitive to eat a high-fat diet to manage fatty liver. But more research highlights the beneficial effects of a high-fat, low-carbohydrate diet on Fatty Liver Disease. A 2018 study evaluated the effects of carbohydrate-restricted induced ketosis in 262 obese or overweight patients.
After one year, participants had improved their blood sugar parameters, reduced their cardiovascular risk factors, and reduced the need for medications to manage high blood pressure and diabetes. Liver enzymes (ALT) used to measure liver health also improved in this trial.
Participants also had sustained weight loss during this trial. Another noteworthy result was a reduction in the diabetes lab test HbA1c, which related to improved liver enzyme levels regardless of weight loss. This highlights the role insulin sensitivity and blood glucose management can play in reducing the risk and worsening of fatty liver.
A 2020 meta-analysis of 154 articles reviewed the benefits of the keto diet on Fatty Liver Disease. The authors concluded, in addition to caloric restriction, macronutrient distribution also plays a role in NAFLD treatment. This means high-fat keto diets had a greater and faster impact on liver fat content than only restricting carbohydrates. The meta-analysis also notes the role ketosis plays in liver fat reduction due to fatty acid oxidation.
Comparing Low-Fat and Low-Carbohydrate Diets: A Systematic Review
A systematic review evaluating low fat vs. low carbohydrate diets for alcoholic fatty liver disease has demonstrated several major findings. Firstly, considering that NAFLD is one of the commonest causes of liver disease worldwide, there is an overall lack of consensus on which dietary intervention is most beneficial for these patients. Secondly, there is also an overall lack of consensus on the definition of the different restrictive diets and the percentage of macronutrient restriction recommended. Moreover, although most of the included papers relate to trials in middle- or high-income counties the diagnostic methods for NAFLD varied.
Hypocaloric diets are associated with improvements in insulin resistance and metabolic syndrome, and consequently have beneficial effects in NAFLD. Both LCD and LFD are able to reduce serum transaminase levels.
A Closer Look at Specific Studies
- LCD vs. Low-Calorie Diet: Two studies compared LCD (<30% from total calorie intake) with low calorie diet. Kani et al. (26) conducted a randomized parallel trial for 30 patients with NAFLD. After intervention with low calorie (−200 to 500 kcal) and low calorie LCD (−200 to 500 kcal, CHO: 45%, FAT: 35%) diets, both ALT and AST decreased. ALP reduction was only seen in low calorie group. Browning et al. (21) compared a very LCD (CHO: 8%, FAT: 59%) with low calorie diet (CHO: 50%, FAT: 34%) in 18 patients with NAFLD. A similar weight loss was observed in both groups. In a single arm study, Benjaminov et al. (32) showed that a 4 week intervention with a very LCD (CHO: 14%, FAT: 56%) did not alter ALT and AST. Significant weight reduction was seen.
- LFD vs. Mediterranean Diet: From four studies, three of them compared LFD with Mediterranean diet and one study had no control group. In a crossover study, 20 patients with NAFLD underwent 16 weeks of MD (CHO: 40%, FAT: 40%), 16 weeks of wash-out period, and 16 weeks of LFD (FAT: 18%, CHO: 62%) (34). Both diet interventions were calorie restricted (1,400 kcal). At the end of the MD period, significant weight loss and ALT and AST reduction were observed. But in the LFD group, there were no significant changes in body weight or transaminases. Serum transaminases and body weight at the beginning of LFD period were the same as the end point of MD period: consequently the conditions at the start of the LFD period differed from that of the MD group. Properzi et al. (35) compared LFD (FAT: 30%, CHO: 50%) and MD (CHO: 40%, FAT: 35-40%) in a parallel-group RCT. Fifty-six patients with NAFLD were recruited and after 12 weeks intervention data from 49 subjects were available for analysis. At the end of the study, ALT and GGT decreased significantly in both groups. Similar weight loss amounts were seen also, with no no significant differences seen at the final analysis.
- LCD vs. LFD: Six interventional studies evaluated liver enzymes levels by comparing LCD and LFD. Rodríguez-Hernández et al. (28) enrolled 31 obese women with NAFLD in a randomized crossover study. They showed that 24 weeks of LCD (CHO: 45%, FAT: 28%) decreased ALT and AST more than LFD (FAT: 21%, CHO: 54%), but there was no statistical significance. Arefhosseini et al. (29) compared LCD (CHO: 40%, FAT: 40%) with LFD (FAT: 25%, CHO: 55%) in 44 overweight patients with NAFLD patients over 6 weeks. The results arising showed that, regardless of the type of diet, calorie deficit (−500 kcal/day) can reduce AST. Unlike the study conducted by Hernández et al. (28), it was only significant for the LFD.
According to the available studies, both LCD and LFD have same effects on liver enzymes in patients with NAFLD. It seems that low caloric diets regardless of their fat and carbohydrate composition are more effective for reduction in liver enzymes. Hypocaloric diets are associated with insulin resistance and metabolic syndrome improvement, so they are effective in reversal of the changes seen with NAFLD. Haufe et al. (23) in their comparative study showed that the reduction of liver fat following hypocaloric LCD (CHO: 25%, FAT 45%) and hypocaloric LFD (FAT: 27%, CHO: 52%) was similar. Patients with higher baseline intrahepatic fat (IHF) achieved a greater reduction of IHF in this study.
Low-Carb, High-Fat Diet and NAFLD: A Promising Approach
A low-carbohydrate, high-fat (LCHF) diet reduced the progression of nonalcoholic fatty liver disease (NAFLD), and despite no calorie restriction, participants with both NAFLD and type 2 diabetes lost 5.8% of their body weight, according to a randomized controlled study.
Based on these results, the LCHF diet may be recommended to people with NAFLD and type 2 diabetes. Basically, if you have fat in your liver, you will benefit from eating fat. The LCHF diet was compared with a low-fat, high-carbohydrate diet more typically followed for these conditions. The low-fat diet was also found to reduce the progression of NAFLD, but to a lesser extent than the LCHF diet.
Those on the LCHF diet consumed an average of 61% energy from fat, 13% from carbohydrates, and 23% from protein, compared with the low-fat diet, which comprised an average of 29% energy from fat, 46% from carbohydrates, and 21% from protein.
The LCHF diet was primarily comprised of unsaturated fats - for example, avocado, oil, nuts, and seeds - but also included saturated fats, such as cheese, cream, and high-fat dairy products.
General Dietary Recommendations for Fatty Liver Disease
Following a well-rounded, nutritious diet rich in fiber, lean or plant-based protein, and healthy fats is the best way to improve liver health, lower disease risk, and promote healthy weight loss.
In general, the diet for fatty liver disease includes:
- Fruits and vegetables
- High fiber plants like legumes and whole grains
- Significantly reducing your intake of certain foods and beverages, including those high in added sugar, salt, refined carbohydrates, and saturated fat
- Limited alcohol
A nutrient-dense, whole-food-based diet rich in fiber, protein, and unsaturated fats is generally recommended for people with NAFLD.
Here are a few foods to include in your healthy liver diet:
- Spinach and other leafy greens
- Salmon, sardines, tuna, trout, and other fish rich in omega-3 fatty acids
- Oats and other high fiber foods
- Walnuts
- Turmeric and curcumins
- Sunflower seeds and other sources of vitamin E
- Garlic
- Coffee
Your healthcare professional may recommend cutting back on less nutritious foods and beverages known to cause weight gain, as well as anything associated with increased blood sugar. This often includes:
- Beer, wine, liquor, and other alcohol
- Foods with high levels of added sugar, such as candy, sodas, and fruit juices
- Fried or highly processed foods, such as bread, rice, and pasta made from white flour
- Red meat, especially beef and pork, and other sources of added sodium
Lifestyle Changes to Improve Liver Health
In addition to modifying your diet, here are a few other lifestyle changes you can make to improve your liver health:
- Get active: Regular exercise can help you lose weight and manage your liver disease. Aim to get at least 30 minutes of aerobic exercise on most days of the week.
- Lower blood lipid levels: Watch your saturated fat and sugar intake to help manage your cholesterol and triglyceride levels. If diet and exercise changes aren’t enough to lower your cholesterol, consult a healthcare professional about your options for medication.
- Manage diabetes: Diabetes and fatty liver disease often occur together. A balanced diet and regular exercise can help you manage both conditions. If your blood sugar is still high, a healthcare professional can prescribe medication to lower it.