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Short-term fasting and a low-carbohydrate diet are both effective treatments for fatty liver disease

More and more people are afflicted with fatty liver disease, a condition that increases the risk of liver cancer and cirrhosis, among other things. A study that the Dietary Science Foundation helped fund has shown that both short-term fasting and a low-carbohydrate diet can radically reduce liver fat amounts. Half of the participants were cured of their fatty liver, thereby preventing long-term liver damage.

A dramatic rise in the number of people with non-alcoholic fatty liver disease follows in the footsteps of the obesity epidemic. Approximately half of those with type 2 diabetes have fatty liver disease, which leads to an increased risk for both liver cancer and cirrhosis of the liver.

Though the disease is common there is no effective medical treatment. Admittedly, fatty liver can be cured by weight reduction and keeping the weight off, and patients are often recommended to reduce calories and cut down their intake of alcohol and sugar. But few people manage to reverse their disease. In a study published in the journal JHEP Reports, researchers at the Karolinska Institute in Sweden investigated whether popular diets such as 5:2 and a low-carbohydrate diet might better help these patients. 

“One of the basic questions we wanted to answer was if a high fat diet such as LCHF would be less effective for treating a fat-related disorder like fatty liver. Our main conclusion is that the diets are equally effective,” says gastroenterology specialist Magnus Holmer, who led the study.

LCHF and 5:2-diet halved the amount of liver fat

The study included a total of 74 patients who were randomized into three groups: a control group that received conventional standard-of-care dietary recommendations, and two diet groups. Participants in the 5:2 group fasted two days a week, eating just 500-600 calories on those days. The LCHF group was instructed to limit their carbohydrate intake to a maximum of 10 percent of total calories. The total calorie intake for the LCHF group was the same as the 5:2 group, but spread over the whole week.

After three months the researchers measured how liver fat had been affected. Participants in both diet groups had halved their amount of liver fat, and about half of them had been cured of the disease. In the control group, liver fat was reduced by 16 percent, and just 8 percent had been cured.

Risk factors for cardiovascular disease improved

Aside from having a positive effect on liver fat, both diets improved participants’ blood sugar levels, as well as several risk factors for cardiovascular disease and type 2 diabetes. “Bad” LDL cholesterol went down on the 5:2 diet, while the LCHF diet had no significant effect on that marker. But the LCHF diet raised levels of “good” HDL cholesterol; a positive change in lipid status that corroborates with findings from earlier studies [1-4].

In an independent comment on the study, Philipp Kaldis, professor at the Department of Clinical Sciences at Lund University was of the opinion that anything that helps people with fatty liver reduce their weight is good:

“You can tell people to eat less, of course, but for some reason it doesn’t work. Reducing calorie intake just two days a week, as in the 5:2 diet, is probably a more feasible strategy. As far as LCHF goes, it’s likely that the fat gives greater satiety and you eat less for that reason,” he says.

Differences between the two dietary treatments

One difference between the two diets is that 5:2 diet reduced liver stiffness, but the LCHF diet did not. That may indicate that a 5:2 diet reduces the long-term risk for developing damaging scar tissue, liver fibrosis. But the method used in the study to measure liver stiffness gives a limited amount of information, and both Philipp Kaldis and Magnus Holmer advise for the results be interpreted with care. More studies are needed. 

When the researchers measured blood pressure, the LCHF diet had the advantage. On that diet blood pressure was significantly reduced, which also reduces the risk for cardiovascular disease.

A third difference between the diets was that some of the participants had digestive issues, acid reflux and slight nausea on the LCHF diet. On the 5:2 diet participants experienced tiredness and hunger on fasting days. One participant (4%) dropped out of the 5:2 diet, while five participants (20%) dropped out of the LCHF diet. The drop-out rate in the control group was 17%.

New tools for managing fatty liver disease

At the end of the study, participants were encouraged to follow the diet they were most comfortable with. Magnus Holmer met with the participants one year later:

“Some of the participants chose a combination of LCHF and 5:2. You should do what works for you and your well-being. Some people have physically demanding jobs, which makes the 5:2 diet harder to follow. For those who prefer a vegan diet LCHF is not an option. A dietary treatment needs to work for the individual patient, so a pragmatic approach is necessary,” Magnus Holmer says.

According to Philipp Kaldis it’s important to keep an eye on blood lipids when following a LCHF diet: “High fat diets are controversial, and there are concerns about their long-term effect on lipid levels.

Earlier studies that have evaluated the effects of a LCHF diet for one and two years [1, 2, 4, 5] found that levels of the bad LDL cholesterol were at the same level as the control group. In a few studies it went up a little [6], but there were also two positive changes: the good HDL cholesterol went up and triglycerides went down. The Dietary Science Foundation has contributed to another two-year study that is evaluating the effect of a LCHF diet for obesity. The results of that study will be published in 2021.

The study contributes important knowledge to health care

Philipp Kaldis and Magnus Holmer both view LCHF as being a healthy diet as long as the individual has good blood lipid and blood sugar levels and their weight is stable.

The Dietary Science Foundation sees the results as positive. The study contributes important knowledge to health care:

“Many of my patients have dangerously high levels of liver fat and there are no drugs that can help them. This study shows that you can quickly reduce the amount of fat in the liver using diet, which will prevent high blood sugar and high blood pressure, liver damage and cancer,” says Kerstin Brismar, professor of diabetes research at the Karolinska Institute and chair of the Dietary Science Foundation’s scientific advisory board.

We want to thank everyone who supports the Dietary Science Foundation. Your contributions have allowed us to help finance this much-needed study. Let’s keep supporting important research!


1. Guldbrand, H., et al., In type 2 diabetes, randomisation to advice to follow a low-carbohydrate diet transiently improves glycaemic control compared with advice to follow a low-fat diet producing a similar weight loss. Diabetologia, 2012.

2. Tay, J., et al., Comparison of low- and high-carbohydrate diets for type 2 diabetes management: a randomized trial. Am J Clin Nutr, 2015. 102(4): p. 780-90.

3. Veum, V.L., et al., Visceral adiposity and metabolic syndrome after very high-fat and low-fat isocaloric diets: a randomized controlled trial. Am J Clin Nutr, 2017. 105(1): p. 85-99.

4. Bazzano, L.A., et al., Effects of low-carbohydrate and low-fat diets: a randomized trial. Ann Intern Med, 2014. 161(5): p. 309-18.

5. Saslow, L.R., et al., Twelve-month outcomes of a randomized trial of a moderate-carbohydrate versus very low-carbohydrate diet in overweight adults with type 2 diabetes mellitus or prediabetes. Nutr Diabetes, 2017. 7(12): p. 304.

6. Gardner, C.D., et al., Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial. JAMA, 2018. 319(7): p. 667-679.