After weight-loss surgery, changes in bile acids seem to help clean up fat in the liver and improve how the liver responds to insulin—even when people haven’t lost much weight yet.

After weight-loss surgery, the body produces more of certain digestive fluids called bile acids, and they change type—this change is linked to better blood sugar and liver health.

After gastric bypass surgery, liver fat levels did not decrease significantly even though patients lost a lot of body fat, but when people lost the same amount of weight by eating fewer calories, their liver fat dropped substantially. This suggests that the method of weight loss affects liver fat differently.

Losing weight—whether by eating better, exercising, taking medicine, or having weight-loss surgery—can help reduce fat, inflammation, and scarring in the liver of obese people with fatty liver disease.

If you're overweight and have too much fat in your liver, just changing to a healthier diet—without losing weight—might actually reverse early fatty liver in as little as two weeks.

If you're an obese adult with fatty liver disease, switching to a very low-carb, high-fat diet for just two weeks might cut your liver fat by nearly half—and you could see improvements in as little as one day.