Same weight lost, different liver

What did the trial do?

Researchers at Washington University in St. Louis put adults with obesity, prediabetes and fatty liver on one of three diets. A ketogenic diet, with almost no carbohydrate. A Mediterranean diet. A very-low-fat, plant-forward diet.

The team supplied all of the food. They adjusted calories until every group had lost about 10% of body weight, which took four to five months.

Holding the weight loss equal is the point. Most diet trials ask which diet loses more. This one took that question off the table to see what the same loss did.

What changed, and what did not?

Some things moved the same for everyone. Muscle insulin sensitivity rose about 50% in all three groups.

The liver did not move the same. On the ketogenic diet, the liver's insulin sensitivity rose two to three times more than on the other two. Liver fat, the liver's own fat production, HbA1c, and blood sugar and insulin across 24 hours all fell most in that group.

Cholesterol did not separate the diets. LDL, apolipoprotein B and 24-hour triglycerides came out the same.

Does this make keto the better diet?

Not on this evidence. Four limits sit right next to the result.

• One small trial. The institution reported 42 people. The abstract gives no number.
• One kind of person. Everyone in it had prediabetes and fatty liver. It says nothing about anyone without both.
• Protein probably was not equal. Work it out from the carbohydrate and fat shares the institution published and protein comes to about 23% of calories on the ketogenic diet, and about 15% on the other two. Part of the liver result may belong to protein, not to cutting carbohydrate. The abstract does not say, and we have not been able to read the paper's diet table.
• Food was supplied. People ate each diet exactly as written. Eating it at home, for years, is a different test.

Press coverage quoted 67% less liver fat and half the group no longer prediabetic. Those figures are not in the abstract, so they are not in this piece.

How does it fit with what was already known?

It sits on top of the older finding, not against it. Across 48 randomized trials, named diets differed little in weight lost, next to the difference between dieting and not dieting at all. A 609-person trial found neither genotype nor insulin secretion picked the better diet for anyone.

That still holds here. Every group lost the same. What this trial adds is smaller and more specific. The same loss is not always the same inside, at least for people whose liver and blood sugar are already under strain.

MVIII keeps every food pattern it offers, and it does not choose one for you.

Next: Is the GLP-1 effect just eating less?

Sources

1. Petersen MC, et al. Effect of diet macronutrient content on the cardiometabolic response to weight loss: A randomized clinical trial. Cell Metab. 2026. https://doi.org/10.1016/j.cmet.2026.07.020
2. Complex Effects of Dietary Manipulation on Metabolic Function, Inflammation and Health. ClinicalTrials.gov NCT02706262. https://clinicaltrials.gov/study/NCT02706262
3. Johnston BC, et al. Comparison of Weight Loss Among Named Diet Programs in Overweight and Obese Adults: A Meta-analysis. JAMA. 2014. https://doi.org/10.1001/jama.2014.10397
4. Gardner CD, et al. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial. JAMA. 2018. https://doi.org/10.1001/jama.2018.0245
5. Institution release as republished by ScienceDaily, 29 August 2026 (source of the 42-person count, the macronutrient shares and the 4-to-5-month timeline). https://www.sciencedaily.com/releases/2026/08/260828082327.htm

General fitness and wellness information, not medical advice. Nothing here substitutes for assessment by a qualified clinician.

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