A new study warns that drinking even a single can of a “diet” or sugar-free soft drink each day can significantly raise your risk of developing serious liver disease. This challenges the common belief that diet drinks are a harmless alternative to sugary sodas and suggests that both regular and “zero-sugar” fizzy drinks deserve caution.
What Did the Study Show?
Researchers followed 123,788 adults who began the study with healthy livers. Over roughly a decade, participants reported their daily beverage consumption using repeated dietary questionnaires.
At the end of the observation period:
- 1,178 participants developed a form of fatty-liver disease known as metabolic dysfunction–associated steatotic liver disease (MASLD).
- 108 participants died from liver-related causes.
The risk shift was notable:
- Those who drank sugary sodas had ~ 50% higher risk of MASLD.
- Those who drank low- or no-sugar (diet) beverages had ~ 60% higher risk — a slightly greater increase.
- Most strikingly, the study showed that even modest intake — roughly one can (about 250–330 ml) per day — was enough to elevate risk.
- Furthermore, participants who replaced these soft drinks with plain water experienced a significant reduction in their liver-disease risk.
Why Diet Drinks Aren’t Necessarily Harmless
It has long been assumed that “diet” sodas — with artificial sweeteners instead of sugar — are a better, safer choice. But the study’s findings complicate that assumption. According to the researchers, sugary drinks contribute to liver fat accumulation through known metabolic pathways: rapid blood-sugar and insulin spikes, weight gain, and increased uric acid, all of which can promote fat storage in the liver.
On the other hand, diet drinks — though low in calories — may impact the liver indirectly: altering gut microbiome, disturbing signals of satiety (fullness), increasing cravings for sweet or high-calorie foods, and possibly stimulating insulin secretion. These mechanisms could also encourage fat buildup in liver cells. Because of this, the assumption that “no-sugar equals safe” does not necessarily hold up under scrutiny.
What This Means for Everyday Drinking Habits
Given the new evidence, relying on diet sodas — or regular sugary sodas — as everyday beverages appears risky, especially if consumed daily. Health experts suggest it’s wiser to minimise intake of both sugar-sweetened and artificially sweetened drinks. Instead, opting for water, sparkling water, or unsweetened drinks can be much better for liver health. Swapping just one daily soda for water might lower your risk of developing fatty-liver disease.
Broader Implications: Re-thinking “Diet” Choices
This research adds to a growing body of evidence that “diet” products are not always a benign shortcut to better health. The findings urge people — consumers and health professionals alike — to reconsider the way soft drinks are viewed in diets. As liver disease becomes increasingly common worldwide, even small daily choices — like what you drink — may have long-term consequences. Drinking water, not soda (diet or otherwise), emerges as the most liver-friendly, metabolism-friendly hydration option.
Conclusion
The findings presented in the study make one message clear: both sugary and diet soft drinks can pose a real threat to long-term liver health. Even a single can a day — whether sweetened with sugar or artificial substitutes — was linked to a significantly higher risk of developing fatty-liver disease. While the mechanisms behind these risks may differ, the outcome is the same: regular consumption of fizzy drinks, regardless of type, may contribute to harmful changes in the body. What stands out most is that replacing these beverages with water noticeably reduced risk, showing that simple daily choices can have a powerful impact on health. As liver disease becomes more common globally, this research serves as a reminder to rethink everyday habits and avoid relying on “diet” labels for safety. Choosing water or unsweetened drinks is not just a healthier option — it may be a vital step in protecting long-term liver function and overall well-being.
