According to a news study released Sunday, the scientists from Purdue University in West Lafayette, Indiana, found that food containing calorie-free artificial sweeteners may be fattening instead of sliming, the Los Angeles Times reports.

The research, performed on rats, was published in the February issue of Behavioral Neuroscience, which is published by the American Psychological Association.

The experiment, funded by the National Institutes of Health and by Purdue, involved nine rats which were given yoghurt sweetened with saccharine, and eight which received yoghurt sweetened with glucose, that is similar to sugar. After receiving yoghurt, the rats were given food. After five weeks, the researchers found that the rats that had been fed sugar-free yoghurt gained averagely 88 grams, while the rats that had consumed glucose-sweetened yoghurt gained 72 grams. The difference is about 20%.

Also, the body temperature of those taking the artificial sweetener showed a lower rise in body temperature, than those taking glucose.

Susan E. Swithers, an associate professor of psychological sciences at Purdue University, said that sweet tastes play the role of informing the body about the calories it is about to receive, preparing the digestive system. But when sweet tastes are not followed by calories, as in the case of artificial sweeteners, the body may get confused and may find it hard to control its appetite.

The study was performed only for saccharine, but researchers say that the effects might be similar in the case of other artificial sweeteners such as aspartame, sucralose and acesulfame.

Previous research has suggested that people who drink diet soda have higher blood sugar, and tend to get fat. According to Lyn M. Steffen, an associate professor of epidemiology at the University of Minnesota, who was not involved in the latest report, said that diet soda may be linked to obesity. The American consumers of products containing sugarfree sweeteners such as soda or yoghurt, almost doubled, from 70 million in 1987 to 160 million in 2000. Coincidently, during the same period, obesity percentage among American adults rose from 15% to 30%.

However, the report’s findings were rejected by Beth Hubrich, a dietitian with the Calorie Control Council, representing companies which make diet foods and drinks.

“The causes of obesity are multi-factorial. Although surveys have shown that there has been an increase in the use of 'sugar-free' foods over the years, portion sizes of foods have also increased, physical activity has decreased and overall calorie intake has increased,” she said, according to Daily Mail.