A ketogenic diet cuts liver fat by an average of 67% in adults with obesity and prediabetes, according to a clinical trial published August 27 in the Cell Press journal Cell Metabolism. Researchers at the Washington University School of Medicine in St. Louis found that this very low-carbohydrate eating plan provided stronger metabolic benefits than either a Mediterranean diet or a low-fat diet, despite participants across all groups achieving a comparable 10% reduction in body weight.
Comparing Diets for Obesity and Prediabetes Treatment
An estimated 40% of adults in the United States live with obesity, according to background data outlined by the study authors. While doctors frequently recommend low-fat, low-carbohydrate, or Mediterranean diets for weight loss, researchers previously lacked clear data on whether one specific dietary approach offered distinct metabolic advantages independent of total weight loss. To evaluate these differences, corresponding author Samuel Klein and his colleagues at Washington University enrolled 42 participants who had obesity, prediabetes, and fatty liver disease.
The research team supplied all food for the participants, and a dietitian met with each individual weekly to ensure adherence to their assigned regimen. The trial evaluated three distinct nutritional structures:
- Ketogenic diet: Supplied 4% of calories from carbohydrates and 73% from fat.
- Mediterranean diet: Supplied 50% of calories from carbohydrates and 35% from fat, emphasizing plant-based foods, olive oil, nuts, fish, and dairy.
- Low-fat plant-forward diet: Supplied 70% of calories from carbohydrates and 15% from fat.
Investigators adjusted calorie intake individually so that participants in every group lost roughly 10% of their body weight over a four-to-five-month period. By the conclusion of the intervention, all participants significantly reduced their body fat and improved their insulin sensitivity.
Ketogenic Diet Liver Fat and Metabolic Changes
Despite matching weight loss outcomes across the cohorts, the ketogenic diet produced superior improvements in several key markers of liver and metabolic health. Liver fat dropped by an average of 67% among participants following the ketogenic diet. By comparison, liver fat fell by an average of 45% in both the Mediterranean and the plant-forward diet groups, according to the trial data.
To understand the physiological mechanisms behind these changes, researchers tracked participant metabolism over 24-hour periods via serial blood analyses. Individuals in the ketogenic group exhibited the largest increase in glucagon, a hormone that assists in reducing stored fat within the liver. They also experienced the greatest decline in blood insulin levels compared to participants on the other dietary plans.
“The most surprising finding was that participants in the ketogenic diet group didn’t experience an increase in blood fat or cholesterol levels despite consuming the most fat,” Max Petersen, the study’s first author at Washington University, stated in the findings.
Prediabetes Remission Rates Across Diet Groups
The clinical trial also tracked the proportion of participants who reversed their prediabetes status following the weight loss intervention. About 50% of participants following the ketogenic diet no longer met the clinical criteria for prediabetes by the end of the study.
In contrast, prediabetes remission occurred in 29% of participants assigned to the Mediterranean diet and 7% of those following the low-fat plant-forward diet. The study data indicate that restricting carbohydrate intake yields therapeutic effects on metabolism and liver fat content that extend past the benefits of weight loss alone for individuals managing obesity and prediabetes.