Scientific research claiming that diet drinks could be better than water at helping people lose weight was funded by an industry body which includes Coca-Cola and PepsiCo among its members, it has emerged.

The study highlighting the benefits of diet drinks, led by Peter Rogers, professor of biological psychology at Bristol University, was published in the International Journal of Obesity.

The scientific review was backed by a research institute, ILSI Europe. It was funded by the institute whose members include Coca-Cola and PepsiCo. Representatives from both companies also sit on the eating behaviour and energy balance taskforce and that the lead author, Professor Rogers, is co-chairman of the taskforce. But the published paper does not disclose that it has given some of the co-authors fees of around £750 each.

Its findings, released last November, were in contrast to other independent research associating diet drinks with weight gain. And Bristol University did not disclose the industry funding in its press release announcing the results of the study, according to the Sunday Times.

Although more than 5,500 papers were reviewed, the comparison of diet drinks with water was based on just three. Two did not find any significant statistical difference in weight loss, and only one paper, funded by the American Beverage Association, found that those drinking diet drinks were more likely to lose weight.

Cardiologist Dr Aseem Malhotra, advisor to the National Obesity Forum, told The Independent: “To suggest that diet drinks are more healthy that drinking water is laughable unscientific nonsense.” He added: “If you want good science you cannot allow corporate sponsorship of research.”

In a statement, a spokesperson for the University of Bristol said: “This research was published in the International Journal of Obesity, a peer-reviewed journal, which means the data and conclusions have been scrutinised by other scientists. We therefore stand by the findings. It was funded by a range of bodies including the NHS and European Union, as well as ILSI Europe.”