MASH can lead to scarring and even permanent liver damage. It can also lead to liver failure or cancer -- increasing the risk of transplant or chemotherapy -- and significantly raise the risk of liver-related death.
The condition is believed to affect an estimated 1.5% to 6.5% of U.S. adults, according to the NIDDK.
In the study, published Wednesday in the New England Journal of Medicine and conducted by researchers in the U.S., U.K., Denmark, France. Italy and Germany, patients received doses of semaglutide, the active ingredient used to treat diabetes in Ozempic and obesity in Wegovy.
The patients started on low doses and increased gradually, reaching the full Wegovy dose over 72 weeks.
Boxes of Wegovy made by Novo Nordisk are seen at a pharmacy in London, March 8, 2024.
Researchers found that about two-thirds of patients had less liver inflammation, and about one-third had improvement in liver scarring, a more advanced stage of damage. Additionally, one-third of patients improved in both inflammation and scarring.
These benefits appeared in people with and without diabetes. Patients also lost an average of 8.5% of their body weight during the 72-week study.
"We knew from studies of lifestyle interventions that as little as five to 10% weight loss was associated with substantial improvements in liver fat and MASH," Dr. Robert Brown Jr., chief of gastroenterology and hepatology at Weill Cornell Medicine in New York City and who was not involved in the study, told ABC News.
In addition to direct health issues, MASH is linked to metabolic syndrome -- a group of conditions including high blood pressure, high blood sugar, excess belly fat and unhealthy cholesterol levels. Metabolic syndrome raises the risk of heart disease, stroke and diabetes.
MASH falls within a larger category of liver disease called Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD), a fatty liver disease which affects about 24% of U.S. adults, according to the NIDDK.
"It's a problem because obesity and Type 2 diabetes have been increasing in this country year over year for decades," Brown said. "And so right now, it's estimated that one-third of the population ... has obesity or Type 2 diabetes. So that's over 100 million people."
The U.S. Food and Drug Administration approved the medication resmetirom for treatment of MASH in 2024, but the response observed in both inflammation and scarring was more modest in comparison to what was seen with Wegovy, according to FDA data.
Brown said people can lower their risk for fatty liver disease by eating healthy meals, staying active and losing weight. Drinking filtered coffee, without too much sugar or cream, may also help protect the liver, he said.
Wegovy addresses the root cause of metabolic syndrome and fatty liver disease by helping regulate blood sugar, reduce body fat and improve insulin sensitivity, the study authors suggested. These changes can ease the strain on the liver and reduce the buildup of fat that leads to inflammation and scarring.
"MASH and MASLD are going to be an increasing health burden, and we are going to need drugs that target the liver fibrosis as well as the underlying metabolic parameters," said Brown. "I'll be excited when we have multiple different drugs that work in different ways, so that we can treat all of the patients who had this problem in the future."
Dr. Allen Chang is the chief resident of the geriatric medicine subspecialty residency program at Dalhousie University and a member of the ABC News Medical Unit.
