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Drinking sugary drinks is associated with weight gain due to their high kilojoule content. This can lead to health concerns like obesity, dental decay and at least 13 types of cancer.

But there is an alternative: ‘diet’ or ‘sugar-free’ drinks, which taste sweet without the extra kilojoules. Are they healthier? Let’s look into it.

First, why are sugary drinks so bad for us?

The average 600ml bottle of soft drink contains 16 teaspoons of sugar and about 1000 unnecessary or “empty” kilojoules.  This means that they exceed the World Health Organization 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 your teeth.

We know that regular consumption leads to weight gain, as people don’t usually reduce how much they eat to allow 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 ‘diet’ drinks healthier?

There are many suspicions 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 have been rumours that some artificial sweeteners can cause cancer. There is no evidence to suggest that artificial sweeteners found in ‘diet’ drinks cause cancer. 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. You can read more about artificial sweeteners and cancer here. Can artificial sweeteners cause cancer? | Cancer Council

Do ‘diet’ drinks help you lose weight?

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

Some studies have shown weight loss among those substituting sugar sweetened beverages with ‘diet’ drinks. Other studies have found ‘diet’ drinks are associated with overeating and weight gain. The reason for this is unclear, but thought to be as a result 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.

What do we recommend when choosing a beverage?

Given the mixed evidence on the effectiveness of artificial sweeteners for weight management, we do not recommend swapping sugary drinks for ‘diet’ drinks to reduce your risk of developing obesity-related cancers.

Although they do not contain the same level of kilojoules as their sugar-sweetened counterparts, they can still rot your teeth.

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!

Content developed by Charlie Sheridan, Community Education Project Officer and Karissa Deutrom, Cancer Council SA Accredited Practising Dietitian.

Cancer Council SA is currently running Rethink Sugary Drinks, a campaign aimed at educating South Australians on the sugar content in some of our favourite drinks. For more information visit .


  1. Food Standards of Australia and New Zealand (FSANZ) 2021. Intense Sweeteners. Available at:
  2. 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.
  3. Richard, A and Smith, G 2020. Artificial sweeteners vs sugar. CHOICE. Available at:
  4. World Health Organization 2015. Guideline: sugars intake for adults and children. Available at: