Participants were randomly assigned to one of three weight‑loss plans: a low‑carb ketogenic diet (about 4 % of calories from carbs and 73 % from fat), a Mediterranean diet (around 50 % carbs and 35 % fat), or a low‑fat, plant‑forward diet (roughly 70 % carbs and 15 % fat).

All three groups lost a similar amount of weight, but the keto group showed a far larger drop in liver fat – about 67 % compared with roughly 45 % in the Mediterranean and low‑fat groups.

The same keto participants also improved liver insulin sensitivity two to three times more than the other groups, while muscle insulin sensitivity rose about 50 % across all diets.

Researchers noted that the greater liver‑fat loss in the keto arm was linked to a decrease in the liver’s production of new fat and metabolic changes that indicate more fat burning when carbohydrate intake is very low.

Because of these metabolic differences, around 50 % of the keto group no longer met the clinical criteria for prediabetes, versus 29 % on the Mediterranean diet and only 7 % on the low‑fat diet. The investigators concluded that, for people with obesity, prediabetes and fatty liver, the composition of a weight‑loss diet can shape metabolic outcomes beyond the effect of weight loss alone.