40% of Obese Children in Korea Found to Have Fatty Liver Disease

Four in ten obese children in South Korea have been found to have fatty liver disease, according to medical experts.

Cases of fat accumulation in the liver are rising rapidly even among those who have never consumed alcohol, raising alarms about liver health in children and adolescents.

Ahead of World Obesity Day on March 4, the medical community warned that childhood obesity is no longer just a weight issue but is now linked to metabolic and liver diseases. While obesity was previously identified as a cause of fatty liver, recent research suggests fatty liver itself can worsen metabolic dysfunction.

"The number of patients visiting hospitals for abnormal liver enzyme levels is increasing every year, nearly matching the rise in childhood obesity cases," said Ryu In-hyuk, professor of pediatrics at Seoul St. Mary's Hospital. "Fatty liver has become the most common liver disease in children. I diagnose it almost daily."

The condition was formerly called "non-alcoholic fatty liver disease," referring to fat accumulation in the liver without alcohol consumption. In 2023, the World Hepatology Society officially renamed it "metabolic dysfunction-associated steatotic liver disease (MASLD)" to reflect its connection to systemic metabolic dysfunction rather than simply weight gain.

MASLD encompasses a spectrum ranging from simple fatty liver to steatohepatitis, fibrosis, and cirrhosis. Diagnosis requires the presence of liver fat along with at least one metabolic risk factor, including obesity, abnormal blood sugar levels, hypertension, high triglycerides, or low HDL cholesterol.

Globally, an estimated 7-14% of children and adolescents have the condition. Among obese children, the rate reaches 30-50%. In Korea, more than 40% of obese children are found to have fatty liver, physicians say. The condition is commonly detected in obese patients aged 10 and older but is also diagnosed in children as young as 8 or 9.

Recovery is possible in early stages. Weight loss and improved dietary habits can restore the liver to normal. However, persistent inflammation damages liver cells and leads to fibrosis, making full recovery difficult.

Lifestyle modification is essential. Patients should eliminate carbonated and sugary drinks and reduce consumption of ultra-processed foods. Beverages containing high-fructose corn syrup should be avoided as fructose is directly converted to fat in the liver. Exercise does not need to be strenuous. Starting with 20-minute daily walks and gradually increasing activity is recommended.

A weight reduction of just 3-5% can produce meaningful improvements in liver health. For a child weighing 80 kg, losing 2.4-4 kg can be effective. A 7-10% reduction decreases inflammation, while losing more than 10% can improve fibrosis. Early intervention is crucial given that relatively modest weight loss can yield significant benefits.

However, elevated liver enzyme levels do not always indicate fatty liver disease. "Other serious liver conditions such as hepatitis B, Wilson's disease, and autoimmune hepatitis may be present," Ryu said. "Treatment varies completely depending on the disease, so accurate diagnosis must come first."