Which? senior food researcher Shefalee Loth said in a blog post that calorie-burning soft drink Aspire "calls itself a calorie-burning soft drink and claims you can burn over 200 calories by drinking a can".
UK company Aspire claims on its website that its cranberry flavour "calorie burning soft drink" of the same name (which contains guarana extract, green tea extract and amino acid L-Carnitine) was backed by research undertaken at Leeds Metropolitan University.
"The laboratory utilised a selection of participants - men and women of varying ages and lifestyles to test the calorie burning effect. The subjects were tested at a resting state so we could achieve a result that represented the amount of calories Aspire burnt without any excercise," the company said.
'Staggering' calorie burn
According to Aspire, the study showed that its drink burnt a "vast amount of calories" in every subject, "with a staggering average of 209 calories (Kcals) per can across the board, without increasing the individuals heart rate".
But Loth said Which? was unimpressed. "When we contacted the company and the laboratory for the data that this figure is based on, it transpired that the calorie loss isn't, arguably, as impressive as implied," she said.
Since our bodies burn calories all the time, even when we're resting, Loth said subjects who drank Aspire - as opposed to a placebo - over 3 hours burnt only 27 extra calories, "not as impressive as the 'over 200 calories' [figure] suggests".
Loth noted that the European Food Safety Authority (EFSA) had assessed health claims on beverages (as well as food) since 2008, but that so far around 80 per cent of submitted claims had been rejected.
Digestive health benefits?
Loth also took a pointed out the expense of probiotic drinks, such as Yakult and Actimel, "which claim to have digestive health benefits".
"One person’s daily dose of one of these shot drinks can add up to £126 to their shopping bill over the course of a year," she said.
Thus far, general health claims linking pre- and probiotics with improved digestive health, gut function and intestinal floral had all been rejected by EFSA, Loth said, with brands beginning to change their advertising as a result.
But Loth suggested that earlier claims lingered in consumer consciousness: "Gone are the claims of ‘helps your digestive tract’, but the unproven claims of these stronger, earlier adverts stick in many people’s minds," she said.
Many other rejected claims had also come to be accepted as fact by the public over the years, she added. "For example, cranberry juice helps treat urinary tract infections".
And Loth warned about unproven claims that remained: "Once a list of approved health claims is released in 2012, manufacturers will have six months to remove the rejected claims from their packaging. But in the meantime we are still faced with claims that may be unproven."