Is your favourite diet soda really safe? How it effects weight loss in comparison to water, revealed in new study

Diet soda is usually seen by people as an easy way to cut sugar without giving up the taste of a fizzy carbonated drink. But there are concerns about artificial sweeteners which then leads to questions about their long-term health effects, with some studies linking them to metabolic problems and cardiovascular risks. A two-year clinical trial now gives a new finding for people who drink diet beverages while trying to lose weight.

Published in the British Journal of Nutrition, the study by researchers from the University of Liverpool compared the effects of low and no-calorie sweetened beverages with water on weight management. It found out that participants drinking diet beverages lost weight at a similar rate to those drinking water.

What the two-year study found

Researchers had done the study on 493 adults who were overweight or obese and told them to drink either plain water or commercially available diet beverages daily. The drinks contained sweeteners such as aspartame, acesulfame potassium and sucralose.


Along with this, both groups of people also participated in a structured behavioural weight-management programme. By the end of the two-year trial, participants in both groups had lost weight and maintained much of their progress.

Those who were drinking diet beverages lost an average of around 10.6 pounds, compared with 8.2 pounds among participants drinking water. However, the difference was not statistically significant, meaning the study could not establish that diet drinks offered a clear weight-loss advantage or not.

Professor Jason Halford said non-nutritive sweetened beverages offered an effective alternative to sugar-sweetened drinks for people managing their weight and performed equivalently to water over two years.

Why artificial sweeteners remain controversial

Despite the weight-management findings, questions remain about the bigger health effects of artificial sweeteners.

Healthline's review of research on diet soda shows potential concerns involving gut bacteria, tooth enamel, headaches and bone health. Some studies have also suggested that artificial sweeteners could affect appetite regulation and even sugar cravings. But the evidence is different in these areas and more research is needed to understand the effects in humans.

Other research has examined possible links with diabetes and cardiovascular problems. A study published in Current Developments in Nutrition, based on the Northern Manhattan Study, followed 2,019 adults who did not have diabetes at the start of the research. During an average follow-up of 11 years, 368 participants developed diabetes.

The researchers found that daily diet soda consumption was associated with a higher risk of developing diabetes among participants who were overweight or obese. But the association does not prove that diet soda caused the condition, and the study said the overall relationship was partly explained by body mass index.

Should you replace water with diet soda?

The trial at the University of Liverpool will comfort people who drink diet drinks to cut down on their sugar intake. But that doesn’t mean diet soda is healthier than water or settles questions about its possible effects beyond weight control.

The World Health Organization cautioned against the use of no-sugar sweeteners for long-term weight control due to uncertainty about the effects of their long-term use.

If you are a regular diet soda drinker, some alternatives to consider are unsweetened tea, sparkling water or plain water with fruit flavoring. Gradually reducing intake may also make it easier to change drinking habits.