A major study has found that people who regularly drink both sugary beverages and their low- or no-sugar “diet” versions are at a higher risk of developing a serious liver condition called MASLD.
This condition, short for metabolic dysfunction-associated steatotic liver disease, was previously known as non-alcoholic fatty liver disease. The findings were presented at UEG Week 2025 and are based on a long-term study of over 123,000 adults from the UK Biobank.
At the start of the study, none of the participants had signs of liver disease. Their drinking habits were tracked using repeated 24-hour food and drink records. Over a median period of 10.3 years, the researchers followed up to see who developed liver problems. During that time, 1,178 people were diagnosed with MASLD and 108 died from liver-related causes.
The results showed that people who drank more than 250 grams (about one can) per day of sugar-sweetened drinks had a 50% higher risk of developing MASLD.
Surprisingly, those who drank the same amount of low- or no-sugar drinks had an even greater risk—about 60%. While sugary drinks were not strongly linked to liver-related death, the “diet” versions were. Both types were linked to higher levels of fat in the liver.
MASLD happens when too much fat builds up in the liver. It can lead to inflammation and cause symptoms like tiredness, stomach pain, and loss of appetite. It is now the most common liver disease in the world and affects more than 30% of people. MASLD is also becoming a leading cause of liver-related deaths.
Lead researcher Lihe Liu explained that sugary drinks have been questioned for their health effects, but many people still believe that diet drinks are a safe alternative. This study challenges that idea. Liu said that even one can a day of these drinks could increase liver disease risk.
The study also explored how these drinks might cause harm. Sugary drinks can cause quick increases in blood sugar and insulin levels, encourage weight gain, and raise uric acid levels—all of which may lead to liver fat buildup.
Diet drinks, though lower in sugar, might still impact the body by changing gut bacteria, interfering with how full you feel, encouraging sweet cravings, and even increasing insulin levels.
The researchers stressed the need to reduce both sugary and artificially sweetened drinks to protect liver and overall health. Replacing these drinks with water lowered the risk of MASLD—by about 13% for sugary drinks and 15% for diet drinks. However, switching from one type to the other made no difference to the risk.
Liu concluded that the safest choice is to drink water. Unlike sugary or diet drinks, water helps the body stay hydrated without putting pressure on the liver or causing fat to build up.
Next, the researchers plan to study how sugar and sugar substitutes interact with gut bacteria and affect liver health over time, using long-term and genetic studies to better understand the causes.
If you care about liver health, please read studies about simple habit that could give you a healthy liver, and common diabetes drug that may reverse liver inflammation.
For more information about health, please see recent studies about simple blood test that could detect your risk of fatty liver disease, and results showing this green diet may strongly lower non-alcoholic fatty liver disease.
The study is published in Hepatology.
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