Academics from Imperial College London and two Brazilian universities - University of Sao Paulo and Federal University of Pelotas - argue that sugar-free versions of soft drinks may be no better in preventing weight gain than their full sugar counterparts.
"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. However, we found no solid evidence to support this," said Professor Christopher Millett, senior investigator at Imperial College London's School of Public Health.
According to the authors, while some studies show no weight loss, others show a small loss, but those studies were not always well done and were often funded by the soft drinks industry.
The study says that "given their negligible nutritional benefits and potential detrimental health impacts", the environmental impact of manufacturing artificially sweetened drinks should be taken into account.
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However, Alison Tedstone, chief nutritionist at Public Health England, said, "swapping to low or no sugar drinks goes some way" to managing calorie intake and weight.
"It's especially important for young people as they consume three times the amount recommended, mostly from soft drinks. However, maintaining a healthy weight takes more than just swapping one product for another. Calories consumed should match calories used, so looking at the whole diet is very important," she said.
Global beverage companies have been investing in soft drinks, flavoured water, juices and ready-to-drink tea and coffee containing artificial sweeteners in response to the obesity crisis and the outcry over sugar.