A new study has uncovered how regular aerobic exercise might help prevent fatty liver disease—by encouraging the body to turn cholesterol into bile acids.
This process not only aids digestion but may also improve how the body handles sugar and fat. The findings were recently published in the journal Function.
Fatty liver disease, officially known as metabolic dysfunction-associated steatotic liver disease (MASLD), is a growing health concern.
It happens when too much fat builds up in the liver and is closely linked to high cholesterol, Type 2 diabetes, obesity, and insulin resistance.
Left untreated, it can progress to serious liver damage and also raise the risk of heart disease.
Although doctors have long known that regular physical activity helps prevent and treat fatty liver disease, the exact reasons haven’t been fully understood. This study, however, offers important new clues.
Researchers suggest that one key reason exercise works is by boosting bile acid metabolism—an essential way the body removes cholesterol.
Bile acids are made from cholesterol in the liver. They play a vital role in breaking down fats during digestion and send signals that help the body better process both fat and sugar. When you exercise, your body produces more bile acids, which helps get rid of cholesterol and supports healthier metabolism overall.
To explore this idea, scientists studied rats bred to have either high or low natural exercise capacity. All the rats were fed a high-fat diet that typically causes fatty liver. The high-capacity rats produced more bile acids, had more bile acids in their stool, and showed fewer signs of liver damage.
In another part of the study, genetically identical mice were also fed a high-fat diet. Half of them had access to running wheels and exercised daily. These active mice showed the same liver benefits as the naturally high-capacity rats, confirming that exercise itself—not just genetics—offers protection.
Interestingly, in a third group of mice that were genetically unable to produce bile acids, exercise provided no protection at all. This suggests that bile acid production is not just helpful but necessary for exercise to prevent fatty liver.
The researchers concluded that bile acid metabolism may be a key link between physical fitness and liver health. By encouraging bile acid production, aerobic exercise may help protect the liver, lower cholesterol, and even reduce the risk of Type 2 diabetes.
