A randomised trial published in Cell Metabolism on 27 August 2026 reported that a very low carbohydrate ketogenic diet reduced liver fat more than a Mediterranean diet or a low fat, plant forward diet, even though all three groups lost about the same amount of weight. Researchers at Washington University School of Medicine in St Louis randomly assigned 42 adults who had obesity, prediabetes and fatty liver disease to one of the three diets, according to the university's news release, provided all of their food, and followed them for roughly four to five months until each group had lost around 10 percent of their body weight. Liver fat fell by an average of 67 percent in the ketogenic group compared with 45 percent in the other two groups. About half of the ketogenic group no longer met the criteria for prediabetes by the end of the study, against 29 percent on the Mediterranean diet and 7 percent on the plant forward diet.
A small, tightly controlled trial with real limits
The paper, by Max Petersen, Samuel Klein and colleagues, is titled Effect of diet macronutrient content on the cardiometabolic response to weight loss and carries the DOI 10.1016/j.cmet.2026.07.020. It was funded by the National Institutes of Health and the Foundation for Barnes-Jewish Hospital, and the senior author discloses advisory board fees and research support from industry. Press versions of the release differ on the enrolled total, giving 42 in one place and 55 in another, so the exact number is not settled by the material published so far. Either way this is a small trial, and everyone in it was selected because they had obesity, prediabetes and fatty liver disease, so the findings are not evidence about healthy adults. Every meal was supplied by the research team, which is not how anyone eats at home, and the trial ran months rather than years.
What this means in practice
Nothing here tells anyone what to eat. The trial compared three ways of reaching the same weight loss in a group with a specific liver problem, and its most useful finding is arguably the negative one: the researchers reported that blood fats and cholesterol did not worsen on the highest fat diet, which is the outcome they had expected to see move. That kind of result is a reminder that headline diet comparisons rarely survive contact with the detail, and it is worth reading the caveats before letting a study change anything in the products already in your cupboard.
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This article reports published news and research and is for information only. Food supplements are not a substitute for a varied diet or medical care, and no product mentioned is intended to diagnose, treat, cure or prevent any disease. Speak to your GP or pharmacist before changing what you take, especially if you are pregnant, breastfeeding, or taking prescribed medicines.
Sources
- Keto diet has greater health benefits than other popular weight-loss diets, according to clinical trial
- Low-carb diet delivers added liver benefits beyond weight loss
- Effect of diet macronutrient content on the cardiometabolic response to weight loss: A randomized clinical trial, Cell Metabolism (existence, journal and authorship confirmed via the CrossRef API; the publisher page is not openable)