ByDaniella Gray
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The Mediterranean diet is often regarded as one of the healthiest ways to eat
But a new clinical trial suggests that when it comes to improving certain markers of metabolic health, a ketogenic diet may have the edge
Researchers found that people with obesity, prediabetes and fatty liver disease saw greater improvements in liver health and blood sugar levels after losing weight on a ketogenic diet than on either a Mediterranean or plant-based diet
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The ketogenic, or keto, diet is a very low-carbohydrate, high-fat eating plan designed to shift the body into a metabolic state called ketosis, where it burns fat for fuel instead of carbohydrates
Common foods include meat, fish, eggs, full-fat dairy products, nuts, seeds and non-starchy vegetables, while foods such as bread, pasta, rice and sugary snacks are largely restricted
The findings, published in the journal Cell Metabolism, come from a randomized clinical trial that compared the effects of three popular weight-loss diets in adults with multiple metabolic risk factors
A total of 55 participants were enrolled, with 42 completing the study. They were randomly assigned to follow one of three diets: a ketogenic diet, a Mediterranean diet or a very-low-fat plant-forward diet
To ensure participants followed their assigned eating plans, all meals were provided by the research team. Adherence exceeded 95 percent across all groups
Importantly, the researchers designed the trial so that participants in all three groups lost roughly the same amount of weight, around 10 percent of their body weight
This allowed them to investigate whether the composition of the diet itself influenced health outcomes beyond weight loss alone
All three approaches improved health
Weight loss increased muscle insulin sensitivity by about 50 percent regardless of which diet participants followed, and all groups saw reductions in body fat and improvements in several cardiovascular risk factors
However, the ketogenic diet consistently produced larger improvements in several key measures
The researchers found that hepatic, or liver, insulin sensitivity improved two to three times more in the ketogenic group than in either the Mediterranean or plant-forward groups
Liver fat also fell more dramatically, dropping by 67 percent in the ketogenic group compared with roughly 45 percent in the other two groups
Participants on the ketogenic diet experienced greater reductions in blood sugar, insulin levels and glycated hemoglobin (HbA1c), a common marker of long-term blood glucose control
The keto group also recorded the highest rates of prediabetes remission, with 50 percent no longer meeting criteria for prediabetes by the end of the study, compared with 29 percent of those following the Mediterranean diet and 7 percent of those on the plant-forward diet
The ketogenic diet did not appear to worsen cholesterol levels despite containing much higher amounts of fat, including saturated fat
Researchers reported no significant differences between groups in LDL cholesterol or apolipoprotein B, two commonly monitored cardiovascular risk markers
The study does not mean the Mediterranean diet is unhealthy. Rather, it suggests that for people specifically struggling with obesity-related metabolic problems and fatty liver disease, restricting carbohydrates may provide additional benefits beyond weight loss alone
Newsweekreached out to the researchers for comment
Reference
Petersen, M.C., Smith, G.I., Farabi, S.S., Palacios, H.H., Shankaran, M., Hellerstein, M.K., Patterson, B.W. and Klein, S. (2026). Effect of diet macronutrient content on the cardiometabolic response to weight loss: A randomized clinical trial. Cell Metabolism. [online] doi:10.1016/j.cmet.2026.07.020
Contact Newsweek editors on this story: Kara Dolman and Gray R. Thomas
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