The researchers said sweet foods may prompt the body to get ready to take in a lot of calories, but when sweetness in the form of artificial sweeteners is not followed by a large amount of calories, the body gets confused, which may lead to eating more or expending less energy than normal. "The data clearly indicate that consuming a food sweetened with no-calorie saccharin can lead to greater body-weight gain and adiposity than would consuming the same food sweetened with high-calorie sugar," Purdue researchers Susan Swithers and Terry Davidson wrote in the journal Behavioural Neuroscience, published by the American Psychological Association.

"Such an outcome may seem counterintuitive, if not an anathema, to human clinical researchers and health care practitioners who have long recommended the use of low- and no-calorie sweeteners as a means of weight control." Other artificial sweeteners such as aspartame that also taste sweet but do not lead to the delivery of calories may have similar effects, the researchers said. "Animals may use sweet taste to predict the caloric contents of food. Eating sweet noncaloric substances may degrade this predictive relationship," the researchers wrote.

"With the growing use of noncaloric sweeteners in the current food environment, millions of people are being exposed to sweet tastes that are not associated with caloric or nutritive consequences," the researchers added. The research was the latest to examine the question of whether artificial sweeteners - used in many soft drinks and other foods - help or thwart those trying to lose weight. Various studies have offered mixed results.

The new research drew criticism from the food industry. "This study oversimplifies the causes of obesity," Beth Hubrich, a dietitian with the Calorie Control Council, an industry association representing companies that make low- and reduced-calorie foods and beverages, said in a statement. "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," Hubrich added.

The council also said findings in animal studies may not be applicable to people, which the researchers acknowledged. Davidson said the implication of the council's statement, "that they, too, are interested in the health of the public, seems insincere".

"If they were sincere, one might expect that they would be alarmed by findings from animal or human models suggesting that their products might be contributing to the obesity epidemic that continues to expand and do its damage," Davidson said. Reuters