A young mum has told how she lost 45kg in eight months by drinking nothing but 10 to 14 cans of Red Bull a day.

Brooke Robertson shrank from 105kg to 60kg during the drastic diet but said she ended up in hospital after a minor heart attack and has had ongoing health problems.

"I know it doesn't sound too good, but I don't regret it because I got to a weight I was happy with," said the 23-year-old Auckland mother of one.

Robertson put on weight while carrying son Keir, now four, but said she didn't make a conscious decision to go on a Red Bull diet.

"I just started drinking it. I wasn't sleeping, I wasn't eating - I was exhausted.

"I just continued to drink it because it's an appetite suppressant and I noticed I was losing weight so stuck with it."

A handful of dry Honey Puffs was usually her only solid sustenance during the 2006 diet - alongside 800-1120mg of caffeine and 275-385g of sugar a day from the 250ml cans of energy drinks.

Robertson said she shook constantly but managed to keep her addiction secret from family and friends.

"They didn't really know the extent of what was going on. They couldn't work out why I wasn't sleeping too well, but they put it down to the stresses of raising my son. I kept it secret but in the end they were quite concerned."

Two weeks in hospital cured Robertson of her addiction.

"I managed to wean myself off it by being in hospital for that long but I had severe withdrawals - sweating, nausea, shaking. It was an addiction. The doctors stated that."

A Red Bull spokesman denied the drink was addictive and said there was "scientific evidence that caffeine is not addictive".

He said it was available in 148 countries "because health authorities across the world have concluded that Red Bull is safe to consume".

But Red Bull is banned in Norway, Denmark and Uruguay because of health fears.

The full-strength drink was allowed into France only last year after the country lifted a 12-year ban, and then only because of pressure from the European Union. Until then a taurine-free version was sold.

In 2008, researchers from the Royal Adelaide Hospital found just one can of Red Bull could increase the risk of heart attack or stroke.

They found that within one hour of drinking it, people developed symptoms normally associated with cardiovascular disease.

Earlier this year, 21-year-old student Chloe Leach died in an English nightclub after drinking about four cans of Red Bull and several vodka-based caffeine drinks.

Doctors found the caffeine could have triggered a rare heart condition.

Robertson now maintains her 60kg figure in a much healthier way - through exercise and a Weight Watchers diet.

Three years after quitting the Red Bull diet, the cafe worker says she still suffers from the effects.

She has a heart murmur, gets severe pain and cramping in her stomach and bowel and suffers anxiety attacks.

Her doctors told her to stay off Red Bull and other caffeinated beverages, but Robertson admits she still drinks it occasionally.

"I can have one and my heart starts and I get the shakes, so I try not to. It's the same with coffee."