Does using olive oil as the main fat source reduce liver fat?
Extra virgin olive oil as part of a Mediterranean diet measurably reduces liver fat. The effect is modest, and greatest when you also eat slightly fewer calories.
Extra virgin olive oil reduces liver fat in people with a fatty liver, but the effect depends strongly on how you use it. At higher doses, more than 30 to 50 grams per day, extra virgin olive oil improved both liver fat and liver enzyme levels in several studies. Regular, refined olive oil performed noticeably worse in those same studies.
When olive oil is looked at on its own, outside the context of a broader diet, the picture is less clear. Seven studies combined found no clear effect on the values that show how hard your liver is working.
When olive oil is part of a Mediterranean diet, the outcomes are more consistently positive. That eating pattern reduces liver fat, lowers the values that measure liver stress, and makes the liver work a little more smoothly. At the same time, people lost an average of 2 to 3 kilograms. The effects are clear, but modest.
Cutting calories remains the most powerful approach: the more you reduce your intake, the greater the improvement. The effect of olive oil is difficult to separate from the rest of the eating pattern. If you have liver fat problems, discuss this with your doctor or dietitian.
This answer draws on several combined summaries and analyses of studies in people, including analyses of seven to eleven such studies focused on people with a fatty liver. The researchers themselves note that the studies differ considerably from one another in dose, duration, type of olive oil, and dietary context, which makes drawing firm conclusions difficult. The isolated effect of olive oil, separate from a broader Mediterranean diet or calorie reduction, has not yet been well established; future research needs to answer that question independently.