Study Suggests Keto Diet May Provide Greater Benefits for Obesity Management Than Mediterranean Diet

The study involved 42 participants diagnosed with obesity, prediabetes, and fatty liver disease who were randomly assigned to follow one of the three diets: keto, Mediterranean, or low-fat, plant-forward. All meals were provided by the research team, and participants met weekly with a dietitian for dietary adherence support. During the study, the keto diet comprised 4% of calories from carbohydrates and 73% from fat, while the Mediterranean diet included 50% carbohydrates and 35% fat, and the plant-forward diet consisted of 70% carbohydrates and 15% fat. Each participant's caloric intake was managed to achieve a weight loss of approximately 10% over four to five months.

At the conclusion of the study, all groups showed a significant reduction in body fat and improved insulin sensitivity. However, the keto diet group exhibited the most substantial enhancements in liver and metabolic function, with average liver fat reduction of 67%, compared to 45% in the other groups. Max Petersen, MD, the study’s first author at Washington University School of Medicine, noted that participants on the keto diet did not experience increased blood fat or cholesterol levels despite higher fat intake.

Additionally, metabolic monitoring revealed that the keto group had the highest increase in glucagon, a hormone that aids in fat loss, and the most significant decrease in blood insulin levels, contributing to reduced liver fat. By the end of the study, about 50% of participants on the keto diet no longer qualified as prediabetic, in contrast to 29% in the Mediterranean group and 7% in the plant-forward group.

Yesika Garcia, MD, a board-certified endocrinologist not involved in the study, emphasized that while the study was well-designed and delivered important insights, its small sample size and duration limit the generalizability of the findings. She highlighted the importance of weight loss as a key factor in metabolic health, noting that muscle benefits observed were consistent across all diets due to weight reduction.

The keto diet, characterized by high fat, low carbohydrates, and moderate protein, aims to induce a state of ketosis where the body relies more on fat for energy. Typical macronutrient distribution for the keto diet includes 50% to 60% fat, 30% to 35% protein, and 5% to 10% carbohydrates. While the keto diet's popularity has grown due to its potential to reduce metabolic risk, Garcia cautioned that it may not be suitable for everyone and can be challenging to maintain long-term.

In contrast, the Mediterranean diet emphasizes fruits, vegetables, whole grains, nuts, and legumes, and is generally considered more sustainable as a lifestyle rather than a strict diet plan. It has a proven history of preventing diabetes and heart disease. The plant-forward diet also focuses on plant-based foods but does not completely eliminate animal products. Garcia advised that regardless of dietary approach, successful weight loss remains fundamental to improving metabolic health.