A recent randomized clinical trial suggests that dietary macronutrient composition may shape health outcomes beyond the number on the scale, with participants following a very-low-carbohydrate ketogenic diet showing greater reductions in liver fat than those assigned to Mediterranean or very-low-fat plant-forward diets.
Different diets, similar weight loss, different metabolic effects
According to a News Medical report published on August 31, 2026, the study found that when participants lost roughly the same amount of weight, changing the balance of carbohydrates, fats and protein produced strikingly different metabolic responses, particularly in the liver. The findings were based on a randomized controlled trial published in Cell Metabolism.
Researchers compared three diet approaches in adults with metabolically unhealthy obesity, defined in the report as obesity with prediabetes and hepatic steatosis. The study evaluated people after roughly five months on a carbohydrate-restricted ketogenic diet, a Mediterranean diet or a fat-restricted plant-forward diet, with all study food provided and weekly dietitian follow-ups used to support adherence.
Liver fat stood out as the clearest difference
The report says participants following the ketogenic diet demonstrated greater reductions in liver fat than those in the Mediterranean and plant-forward groups. The article also notes that the researchers measured body composition, hepatic lipogenesis, oral glucose tolerance, pancreatic beta-cell function, blood pressure, lipid and triglyceride levels, glucose, cytokines, insulin, glucagon and C-peptide.
The study included 55 randomized individuals, with 42 completing the trial and being analyzed. Each final group contained five men and nine women, with a mean age of 43 years and a mean initial body mass index of nearly 39 kg/m2. The report says the findings could inform future diet planning and nutrition research, especially for people with metabolically unhealthy obesity.
Why the findings matter for nutrition advice
The News Medical report highlights that previous diet studies have often struggled to separate the effects of diet composition from the effects of weight loss itself because adherence is uncertain and weight loss differs between groups. In this case, the controlled provision of food and close follow-up strengthened the comparison between the three dietary patterns.
The article suggests the results may be relevant for clinicians and researchers looking at how diet composition influences cardiometabolic health, especially in people with obesity-related metabolic dysfunction. The report also links the findings to broader concerns about metabolic diseases such as prediabetes and metabolic dysfunction-associated steatotic liver disease.
Even so, the study’s implications remain focused on comparing dietary patterns under controlled conditions rather than offering a one-size-fits-all recommendation. As the report indicates, the key message is that similar weight loss does not necessarily produce identical metabolic outcomes.
For readers looking for the original report, the source article can be found on News Medical.
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