Sugar-free and diet drinks are not helpful for weight loss and could even cause people to pile on the pounds, researchers at Imperial College have claimed.

A review of dozens of studies dating back 30 years found that there is no solid evidence that sugar-free alternatives prevent weight gain, type 2 diabetes or help maintain a healthy Body Mass Index (BMI).

Although artificially-sweetened beverages contain fewer calories than sugary versions, researchers say they still trigger sweet receptors in the brain, which may make people crave food, Health news reported.

Coupled with the fact that most people view diet drinks as healthier, it could lead to over-consumption, the researchers argue.

“A common perception, which may be influenced by industry marketing, is that because `diet’ drinks have no sugar, they must be healthier and aid weight loss when used as a substitute for full sugar versions,” said Professor Christopher Millett, senior investigator from Imperial’s School of Public Health.

“However we found no solid evidence to support this. Far from helping to solve the global obesity crisis, artificially-sweetened beverages may be contributing to the problem and should not be promoted as part of a healthy diet.

“The authors claim that previous studies which found diet drinks were helpful should be discounted because they were funded by the drinks industry.

However the British Soft Drinks Association said that it was wrong to target sugar-free drinks, because they helped people maintain a low calorie diet.