Fatty liver disease, including non-alcoholic fatty liver disease (NAFLD) and its more advanced stage, non-alcoholic steatohepatitis (NASH), have become the fastest-growing reasons for liver transplants among young adults in the United States, Reuters reports.

The troubling findings come out of a recent study analyzing data from the United Network for Organ Sharing (UNOS) published in the Journal of Clinical Gastroenterology. Researchers studied transplant data between 2002 and 2012 and found that more than 5,000 people ages 18 to 40 received a liver transplant in the United States during this time period.

The top reason for a transplant among young adults was for autoimmune/cholestatic liver disease, which accounted for 25 percent of such surgeries. About 18 percent of such surgeries were for acute liver failure. Other important causes for transplants among young adults were hepatitis C virus (HCV) and hepatitis B virus (HBV) infections, as well as liver cancers. NASH accounted for just 3.3 percent of all transplants across the study period, but study authors noted it was by far the fastest-growing reason for a transplant they observed.

More specifically, the number of liver transplants performed for NASH increased from 0.53 percent in 2002 to 4.46 percent in 2012, a ninefold jump. Researchers say increasing rates of childhood obesity, hypertension and diabetes — which exploded in the ’80s and ’90s — are largely to blame.

“I see kids at ages 7 and 8 with this problem, and one of my youngest patients developed cirrhosis at 13,” said senior study author Naim Alkhouri, MD, director of the metabolic program at the Texas Liver Institute in San Antonio. In his home state of Texas, NASH is currently the number one indicator for transplants in young adults.

The report also notes that NAFLD and NASH often go unrecognized and untreated in young patients, since doctors don’t typically look for signs of the disease until individuals are older. And while new studies are investigating ways to treat NAFLD and NASH early in life, the Federal Drug Administration has not approved any medications for the conditions.

Currently, the best ways to prevent transplants in patients diagnosed with fatty liver diseases include weight management, controlling underlying blood pressure and diabetes issues, and generally leading a healthy lifestyle.