A controlled trial reveals that a ketogenic diet not only aids weight loss but also drastically reduces liver fat and improves prediabetes, outperforming Mediterranean and low-fat diets in metabolic outcomes.
Researchers at Washington University School of Medicine have found that a ketogenic diet may do more than help with weight loss in people with obesity, prediabetes and fatty liver disease. In a controlled trial involving 42 adults, the team compared a very low-carbohydrate ketogenic diet with a Mediterranean pattern and a plant-forward, low-fat diet, while providing all meals and adjusting calories so each group lost about 10% of body weight over four to five months. The design was intended to separate the effect of diet composition from the effect of weight loss alone.
The results, as reported in the study summary, suggest that the keto group saw the strongest gains where liver health and blood sugar were concerned. Average liver fat fell by 67% among people on the ketogenic plan, compared with a 45% reduction in both the Mediterranean and low-fat groups. Roughly half of those on keto no longer met the clinical threshold for prediabetes by the end of the intervention, versus 29% in the Mediterranean group and 7% in the low-fat group. All three diets improved body fat and overall insulin sensitivity, but the low-carbohydrate approach appeared to deliver the clearest extra benefit for the liver.
That distinction matters because fatty liver disease and prediabetes are closely tied to metabolic risk, and the trial was structured to test whether macronutrient mix itself can influence outcomes. Samuel Klein, the study’s corresponding author, said the findings indicate that lowering carbohydrate intake may have therapeutic effects beyond the impact of shedding pounds. The report also quoted David Petersen as saying that GLP-1-based medicines have transformed obesity treatment, but that diet composition can still add benefits alongside weight-loss drugs.
Earlier research points in a similar direction, although not always with the same degree of separation between diets. A 2019 paper in the National Centre for Biotechnology Information archive found that ketogenic eating could reduce liver fat in overweight adults, while a 2024 review concluded that keto-style diets may improve liver fat even without calorie restriction in people with metabolic dysfunction-associated steatotic liver disease. Taken together, the evidence suggests that carbohydrate restriction may have a role in targeted metabolic treatment, even as experts continue to weigh practicality, long-term adherence and the needs of people who rely on carbohydrate intake for high-intensity exercise.
For cyclists and other endurance athletes, that trade-off remains important. A lower-carb approach may help some people with liver fat and impaired glucose control, but it can also make it harder to replenish glycogen, the body’s stored form of carbohydrate that is central to hard efforts and repeated training sessions. That means the diet’s promise is clearest in a clinical setting, where the priority is improving metabolic health, rather than in sport alone, where performance demands may argue for a more flexible, periodised approach.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
