Scientists Identify Diet That Reduces Liver Fat and Prediabetes Risk More Effectively Than Others

A ketogenic diet, which severely restricts carbohydrates and is high in fat, may provide greater metabolic benefits for people with obesity than Mediterranean and low-fat diets, according to a clinical trial. The findings were published in the journal Cell Metabolism.

The study involved 42 people with obesity, prediabetes, and fatty liver disease. Participants were randomly assigned to one of three groups: a ketogenic diet, a Mediterranean diet, or a low-fat, predominantly plant-based diet. The researchers provided all of the participants’ meals, and the volunteers met with a dietitian every week.

The diets were designed so that all participants would lose approximately 10% of their initial body weight. On average, this took four to five months.

The three diets differed substantially in their nutritional composition. In the ketogenic diet, carbohydrates accounted for just 4% of total calories, while fat provided 73%. In the Mediterranean diet, carbohydrates accounted for 50% and fat for 35%. In the low-fat plant-based diet, the corresponding figures were 70% and 15%.

All three diets led to a significant reduction in body fat and improved the participants’ insulin sensitivity. However, the ketogenic diet was the most effective on several measures of liver and metabolic health.

For example, liver fat decreased by an average of 67% among participants following the ketogenic diet, compared with approximately 45% in each of the other two groups.

Participants on the ketogenic diet also experienced the largest increase in glucagon, a hormone that promotes the breakdown of fat stores in the liver. At the same time, their blood insulin levels decreased more substantially, which was also associated with a reduction in liver fat.

The differences were particularly notable when it came to prediabetes. After the intervention, approximately 50% of participants in the ketogenic group no longer met the criteria for prediabetes. The figure was 29% in the Mediterranean diet group and just 7% among those following the low-fat plant-based diet.

Despite its high fat content, the ketogenic diet did not lead to increased levels of blood lipids or cholesterol. According to study first author Max Petersen of Washington University School of Medicine, this was one of the most unexpected findings of the research.

The authors emphasize that weight loss itself improves metabolic health in people with obesity. However, the findings suggest that the composition of the diet may provide additional benefits beyond those associated with weight loss alone.

“If a person has a lot of liver fat and prediabetes, reducing carbohydrate intake may have a substantial therapeutic effect on metabolism beyond the effect of weight loss itself,” said study leader Samuel Klein.