A study by Australian academics found those who drank high-caffeine cocktails had a 'stronger desire to keep drinking than if they drank alcohol on its own'.

London - They are popular with revellers watching their waistlines. But diet mixers make you more drunk than sugary alternatives, scientists have warned.

Women are most at risk, as they are likely to order diet mixers to save on calories, researchers said.

When men and women were given vodka mixed with either a soft drink or its sugar-free version, they became intoxicated more quickly on the diet option.

A vodka with diet lemonade took them over the drink-drive limit, while normal mixer did not.

Despite this, drinkers felt no more inebriated and were just as likely to say they were fit to drive.

The US research team had 16 men and women attend their lab to sample the drinks.

Their breath alcohol readings were taken, reaction times were measured and they were asked how drunk they felt and if they were capable of getting behind the wheel.

Northern Kentucky University researcher Cecile Marczinski said: “Alcohol measured with diet mixer results in higher breath alcohol concentration. The subjects were unaware of this difference.”

It is thought sugary drinks, like food, slow the passage of alcohol into the bloodstream.

However, the sweeteners found in diet drinks do nothing to dull booze’s effect.

The researchers warned that lack of awareness about the effect could lead to people unwittingly drink-driving.

In the journal Alcoholism: Clinical & Experimental Research, Dr Marczinski said: “While mixing alcohol with a diet beverage mixer may limit the amount of calories being consumed, higher breath alcohol concentrations are a much more significant health risk than a few extra calories.” - Daily Mail