A KETOGENIC diet may provide metabolic benefits beyond weight loss alone in people with obesity, prediabetes, and fatty liver disease, according to findings from a randomised clinical trial.
Researchers found that although similar weight loss improved metabolic health regardless of diet, severe carbohydrate restriction produced greater improvements in liver fat and blood glucose control than Mediterranean and low-fat, plant-forward diets.
Researchers randomly assigned 55 adults with metabolically unhealthy obesity to one of three diets: a low-carbohydrate, high-fat ketogenic diet; a Mediterranean diet; or a high-carbohydrate, low-fat, plant-forward diet.
The ketogenic diet provided just 4% of energy from carbohydrates and 73% from fat. By comparison, carbohydrates accounted for 50% of energy on the Mediterranean diet and 70% on the plant-forward diet.
Participants received all their food from the research team and attended weekly appointments with a dietitian and calorie intake was adjusted so participants lost approximately 10% of their starting body weight over four to five months.
This allowed researchers to examine whether diet composition produced metabolic effects independent of weight loss.
It was found that weight loss produced substantial benefits across all three groups. Muscle insulin sensitivity improved by approximately 50%, suggesting that losing weight itself was an important factor in improving insulin resistance.
However, differences emerged in the liver. Liver fat decreased by 67% in participants following the ketogenic diet, compared with 45% in both the Mediterranean and plant-forward groups. Improvements in hepatic insulin sensitivity were also two to three times greater with the ketogenic diet.
Researchers suggested that the hormonal response to severe carbohydrate restriction may partly explain these effects.
The ketogenic diet produced the greatest reduction in circulating insulin alongside an increase in glucagon, potentially encouraging the liver to break down stored fat and increase fatty acid oxidation.
Blood glucose control also improved most substantially in the ketogenic group. Average 24-hour blood glucose fell by approximately 20%, compared with around 8% with the other diets.
By the end of the intervention, 50% of participants following the ketogenic diet no longer met diagnostic criteria for prediabetes. This compared with 29% of those following the Mediterranean diet and 7% following the plant-forward diet.
Despite consuming considerably more dietary fat, participants following the ketogenic diet did not experience the anticipated increase in circulating blood fats or cholesterol during the study.
The findings reinforce the metabolic benefits of moderate weight loss while suggesting that macronutrient composition could influence specific outcomes independently.
For people with obesity accompanied by fatty liver disease and prediabetes, the researchers suggest that reducing carbohydrate intake may offer additional improvements in liver metabolism and glucose regulation.
However, the tightly controlled study provided participants with all their meals and regular dietitian support. Further research will therefore be needed to establish whether these benefits can be maintained under real-world conditions and over longer periods.
Petersen M C et al. Effect of diet macronutrient content on the cardiometabolic response to weight loss: A randomized clinical trial. Cell Metabolism. 2026. doi:10.1016/j.cmet.2026.07.020.
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