While diet sodas are often advertised as products that can help one lose weight, a new study suggests that heavy diet soda consumption may increase one’s risk of metabolic dysfunction-associated steatotic liver disease (MASLD, formerly known as non-alcoholic fatty liver disease, or NAFLD) as well as weight gain and type 2 diabetes, Medical News Today reports.

MASLD, which has no initial symptoms, currently affects about 46% of the world’s population.

Often referred to as “silent diseases,” MASLD and metabolic dysfunction-associated steatohepatitis (MASH, formerly known as non-alcoholic steatohepatitis, or NASH) are responsible for a growing proportion of advanced liver disease, mirroring a global rise in obesity. MASLD can lead to liver fibrosis, cirrhosis and even liver cancer. With no effective approved medical therapies, management depends on lifestyle changes such as weight loss and exercise.

Published in BMC Public Health, the recent study suggests a strong correlation between diet sodas that claim to have “zero sugar” and “zero calories” and MASLD. After accounting for several variables, including race, age, gender, diet and cardiometabolic conditions, researchers found that diet soda consumption “was positively associated with the occurrence of MASLD.”

Sweetened beverages, including regular soda, fruit drinks, sports drinks, energy drinks and coffee, are the leading source of added sugars in the American diet, according to the Centers for Disease Control and Prevention.

About 63% of adults drink sugary drinks once daily or more. What’s more, diet sodas often contain artificial or chemical sweeteners, such as aspartame, which the World Health Organization (WHO) classifies as a possible carcinogen.

"Replacing free sugars with [non-sugar sweeteners] does not help with weight control in the long term. People need to consider other ways to reduce free sugars intake, such as consuming food with naturally occurring sugars, like fruit, or unsweetened food and beverages,” said the WHO’s director of nutrition and food safety, Francesco Branca, PhD, in a news release earlier this year.

“[Non-sugar sweeteners] are not essential dietary factors and have no nutritional value,” he added. “People should reduce the sweetness of the diet altogether, starting early in life, to improve their health.”

While experts suggest prioritizing water for hydration, unsweetened coffee and tea are also healthy choices. Consumption of beverages such as fruit juice and sodas should be limited.