MILLIONS of weight-conscious consumers believe it is a healthy choice: low in kilojoules and sugar-free.

But diet cola can make you fat and rot your teeth, according to new research.

A study by consumer group Choice warns drinking artificially sweetened soft drinks can stimulate the appetite, triggering cravings for sweet foods.

Ironically, this can lead to consumers putting on more weight than they would have by drinking regular cola.

"You're more likely to lose weight if you avoid these drinks altogether. Maybe drink water or get your caffeine fix from a cup of coffee," the study says.

And despite having no sugar, diet drinks are not safe for teeth because they contain phosphoric acid or citric acid, which cause tooth enamel to erode.

"It's different from decay, but can be just as bad for your teeth," the report warns.

A can of regular Coca-Cola contains about eight teaspoons of sugar and 675kj.

A can of Diet Coke has less than 10kj, but contains artificial sweeteners, stimulates appetite and increases cravings for sweet foods.

Diet colas usually contain at least two sweeteners that can be many hundreds of times sweeter than sugar.

These can be identified by the code numbers on labels: acesulphame potassium (950), aspartame (951), cyclamate (952), saccharin (954) and sucralose (955).

Some have been linked to increased risk of cancer in rats.

The study, called Diet Cola Myths, also raised concerns about children exceeding the acceptable daily intake (ADI) of the sweetener cyclamate.

"The ADI is the 'safe' level recommended by scientific experts. There's a substantial safety margin and consuming more than the ADI over a short period isn't necessarily a health risk, but on a regular basis there might be cause for concern," the study states.

Cyclamate was banned in some countries until the mid-1990s after a study found it increased the risk of bladder cancer in rats.

Subsequent research has found no conclusive evidence that it poses a risk to humans.

Experts agree the cancer risks of artificial sweeteners are low, especially when balanced against the risks of being overweight, but they do recommend limiting consumption of foods and drinks containing sweeteners.

"Diet cola might not be as helpful in the fight against flab as you'd think, kids risk overdosing on the artificial sweeteners, and it's still harmful for your teeth," the report says.

To establish whether big-name diet colas like Diet Coke and Pepsi Max taste better than cheaper alternatives, Choice conducted a blind taste-test among 277 Sydney shoppers.

Rival brands included generics such as Black & Gold, Australia's Choice, Home Brand and You'll Love Coles.

Tasters were unable to differentiate between the 11 drinks.

No single brand tasted better or worse than average, even among label-conscious groups such as those aged 18 and under.

But big brands are more popular because of their advertising power.

Coca-Cola Amatil spent more than $18 million just on promoting Coke Zero last year, according to Choice.

April 8, 2007