Which Diet Is Best to Lower Liver Fat and Improve Insulin Sensitivity?

A randomized controlled trial enrolled 42 people with metabolically unhealthy obesity (prediabetes, very elevated liver fat ~18-20%, HOMA-IR ~6.8) and randomized them to a very-low-carbohydrate ketogenic diet (4% carbs, 73% fat), a Mediterranean diet, or a very-low-fat plant-forward diet (70% carbs, 15% fat). Weight loss was experimentally matched and outcomes were measured after exactly 10% weight loss, a design that isolates effects of diet composition from weight-change magnitude. The study also documented substantial loss of fat-free mass across groups.

All three diets produced similar total weight loss and improved skeletal muscle insulin sensitivity by roughly 50%, but the ketogenic diet produced markedly larger improvements in the liver: liver fat fell by 67% on keto versus about 45% on the Mediterranean and low-fat plant diets, and hepatic insulin sensitivity increased by roughly 200% on keto versus 50-80% on the other diets. Fasting glucose, fasting insulin, HOMA-IR, and triglycerides improved in all groups but improved most on keto; HbA1c fell modestly across diets. Despite large improvements, liver fat remained above ideal in most participants (around 6-10%) after 10% weight loss. Overall, macronutrient composition mattered for liver-specific outcomes, with the ketogenic approach producing the greatest reductions in liver fat and the largest gains in hepatic insulin sensitivity beyond equivalent weight loss.