According to a clinical trial published in Cell Metabolism on August 27, a ketogenic diet offers significant metabolic and liver health benefits for individuals with obesity compared to the Mediterranean and low-fat, plant-forward diets. While all three eating regimens successfully reduced body fat and improved insulin sensitivity, the keto diet uniquely drove down liver fat by an average of 67% and reversed prediabetes in half of the study participants.
Clinical Trial Design and Macronutrient Breakdown
Researchers at the Washington University School of Medicine in St. Louis evaluated 42 participants with obesity, prediabetes, and fatty liver disease. Samuel Klein, senior author of the study and a professor of medicine and nutritional science, noted that the team focused on health changes after equal weight loss rather than the weight loss itself. As Klein pointed out based on media coverage, those aspects have already been examined in numerous prior investigations, leaving very minor distinctions among these trio of dietary approaches.
The trial provided participants with pre-cooked, frozen meals tailored to specific macronutrient distributions. Participants met weekly with a dietician. The diets broke down as follows:
- Ketogenic diet: 4% carbohydrates, 73% fat, and moderate protein.
- Mediterranean diet: 50% carbohydrates, 35% fat, featuring fish, chicken, legumes, seeds, nuts, and olive oil.
- Plant-forward diet: 70% carbohydrates, 15% fat, focusing on beans, rice, and fruits and vegetables.
Liver Fat Reduction and Metabolic Mechanisms
Participants lost about 10% of their starting weight across all three groups over four to five months. However, the keto group experienced vastly superior liver outcomes. Max Petersen, assistant professor in medicine and the study’s first author, stated that liver fat dropped by 67% in the keto group, compared to 45% in the other groups.
Blood tests revealed that the keto group experienced the largest increase in glucagon, a hormone that promotes fat loss in the liver. They also showed the greatest reduction in blood insulin levels and a decrease in the liver’s production of triglycerides. Furthermore, about 50% of participants in the keto group no longer met the criteria for prediabetes by the end of the study, compared to 29% in the Mediterranean group and 7% in the plant-forward group.
Expert Perspectives on Sustainability and Caveats
External experts urge caution when interpreting the results. Yesika Garcia, a board-certified endocrinologist with Medical Offices of Manhattan who was not involved in the trial, noted that the study was small and lasted only five months. Driven by shedding pounds, all three meal plans yielded the exact same positive impact on muscle tissue, which serves as the primary sugar-metabolizing engine in the human body, Garcia informed Healthline.
Garcia also pointed out that the keto diet is difficult to sustain over long periods. By contrast, the Mediterranean diet maintains a deeper track record for long-term diabetes and heart disease prevention because it functions as an adaptable lifestyle rather than a restrictive plan. Jeff Volek, a kinesiologist at the Ohio State University who was not involved with the research, praised the trial as well-designed.
Pro Tip: Experts recommend prioritizing overall food quality and selecting an eating pattern you can maintain long-term. Always consult a physician before making drastic changes to your carbohydrate or fat intake.
Frequently Asked Questions
- How does the keto diet affect cholesterol?
Despite consuming a diet high in fat, participants in the ketogenic group did not experience an increase in blood fat or cholesterol levels, according to Max Petersen. - Did the diets differ in muscle health benefits?
No. The benefit to muscle tissue was identical across the keto, Mediterranean, and plant-forward diets, driven entirely by overall weight loss. - Is the keto diet suitable for everyone?
Not necessarily. While it provides specific liver and metabolic benefits for individuals with obesity and prediabetes, experts note it is hard to sustain and requires careful medical supervision.
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