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Sugary drinks are high in kilojoules (energy) and low in nutritional value. We know that regularly drinking sugary drinks can cause dental decay as well as lead to weight gain and obesity.  High body weight is a risk factor for serious health problems including type 2 diabetes, heart disease and some cancers.

But what about the alternatives? ‘Diet’ or ‘sugar-free’ drinks, taste sweet but without the added kilojoules. Are they healthier? Let’s look into it.

First, why are sugary drinks bad for you?

The average 600ml bottle of soft drink contains 16 teaspoons of sugar and about 1,000 unnecessary or ‘empty’ kilojoules. This means that they exceed the World Health Organisation’s recommendations for sugar (which is around 12 teaspoons per day for the average adult), they offer little to no nutritional value, plus they’re acidic which is bad for our teeth.

We know that regular consumption of sugary drinks can lead to weight gain, as people usually don’t account for the extra kilojoules coming from sugary drinks.

Sneakily, drink companies have found a way to overcome this concern. They can use artificial sweeteners to sweeten beverages instead of sugar, which contain little to no kilojoules. But are these ‘diet’ drinks any better for us than the sugary drinks they impersonate?

Are sugar-free drinks actually healthier?

There is some concern about the healthiness of artificial sweeteners, with some critics suggesting they may cause more harm than good and are no better than their sugary counterparts. So, what does the evidence say?

Artificial sweeteners are synthetic chemical compounds which provide very few kilojoules and taste intensely sweeter than sugar. This means that when used as a sugar replacement, much less is required to achieve the desired level of sweetness.

There are several types of artificial sweeteners including aspartame, sucralose, cyclamate and saccharin, all of which are approved and regulated by the Food Standards of Australia and New Zealand (FSANZ).

There is limited evidence to suggest that the artificial sweetener, aspartame, causes cancer.

The intense sweetener aspartame, often used in ‘low-sugar’ and ‘diet’ drinks, and other products like confectionery, and yoghurt, has been classified by the World Health Organisation’s (WHO) International Agency on Research on Cancer (IARC) as ‘possibly carcinogenic to humans’. This is based on limited evidence that consumption of aspartame is associated with an increased risk of liver cancer.

There is no current evidence to suggest that other artificial sweeteners found in ‘diet’ drinks cause cancer.

What does this mean for the average person?

This means that aspartame has been found to be a possible cause of liver cancer in humans, but only when consumed in high amounts.

The current Acceptable Daily Intake of aspartame is 40 mg of aspartame per kilogram of body weight per day.

For example, for a can of diet soft drink containing 200 mg of aspartame, a person weighing 70 kg would need to consume more than 14 cans per day to exceed this limit, assuming no other aspartame was consumed from other foods.

Thankfully, research shows that the vast majority of Australians are consuming well below the Acceptable Daily Intake for aspartame.

Food supply in Australia is strictly regulated and the intense sweeteners used in Australia have not been found to increase the risk of cancer in the amounts currently consumed. Additionally, a recent survey (2019) found that the use of aspartame in Australian food and drink products has decreased.

In Australia, FSANZ sets acceptable levels for all types of additives including artificial sweeteners, which are allowed to be used in drinks. These levels are regularly reviewed and adjusted by FSANZ according to the evidence to ensure our safety.

Are sugar-free drinks good for weight loss?

Due to their low kilojoule content, artificially sweetened beverages like ‘diet’ soft drinks are often chosen to help maintain or lose weight. However, the evidence for artificial sweeteners and their effect on weight is inconsistent.

Some studies have shown that people who substitute sugar-sweetened beverages with ‘diet’ drinks, lose weight. Other studies have found ‘diet’ drinks are associated with overeating and weight gain. The reason for this is unclear but thought to be because of either artificial sweeteners not leaving you feeling full, or perhaps a sense of freedom to eat more because you’ve had a low-calorie drink.

Additionally, a recent review by WHO found that replacing sugars with intense low-calorie sweeteners has short-term effects for weight loss, however in the longer term it may be associated with increased risk of type 2 diabetes and cardiovascular diseases.

Is it better to drink sugar-free drinks or drinks with sugar?

Given the mixed evidence on the effectiveness of artificial sweeteners for weight management and the risk of diet-related noncommunicable diseases, we do not recommend swapping sugary drinks for ‘diet’ drinks when trying to achieve or maintain a healthy weight.

Even though ‘diet’ drinks do not contain the same level of kilojoules as their sugar-sweetened counterparts, they can still cause tooth erosion.

We recommend drinking water or low-fat milk. Water is the best option for hydration and low-fat milk provides important nutrients such as calcium and protein, which supports healthy bones and teeth.

At the end of the day, water is naturally sugar free….since forever!

Cancer Council SA’s current Rethink Sugary Drinks campaign aims to educate South Australians on the sugar content of some of our favourite drinks and encourages them to choose water instead. For more information visit


  1. Cancer Council Australia 2023. Information sheet: Intense sweeteners and cancer risk. Available at:
  2. Food Standards of Australia and New Zealand (FSANZ) 2021. Intense Sweeteners. Available at:
  3. Hector et al 2009. Soft drinks, weight status and health: a review. A NSW Centre for Public Health Nutrition (now known as Cluster of Public Health Nutrition, Prevention Research Collaboration, University of Sydney) project for NSW Health, 2009.
  4. Richard, A and Smith, G 2020. Artificial sweeteners vs sugar. CHOICE. Available at:
  5. World Health Organization 2015. Guideline: sugars intake for adults and children. Available at:
  6. World Health Organization 2023. Aspartame hazard and risk assessment results released. Available at:
  7. World Health Organization 2023. WHO advises not to use non-sugar sweeteners for weight control in newly released guideline. Available at: