THURSDAY, July 8, 2004 (HealthDayNews) -- Consuming artificially sweetened foods and beverages may throw off your natural ability to monitor calories and increase your likelihood of overeating.
That's the claim of a new study by two Purdue University researchers that appears in the July issue of the International Journal of Obesity.
Not surprisingly, a spokeswoman for the sweetener industry takes exception to the study, pointing out it was done only on animals and that previous research has found the use of artificial sweeteners actually helps weight-control efforts.
The research, carried out by scientists Susan Swithers and Terry Davidson, involved rats.
"What we are actually suggesting from our study is not that artificial sweeteners are going to make people gain wait," said Swithers, an associate professor of psychological sciences. "They are actually losing an unconscious ability to measure their food intake when they consume artificial sweeteners."
So if people do consume artificial sweeteners, they have to be more conscious of the calories involved when they do eat sweet things, she said.
In the first of two studies by Swithers and Davidson, two groups of rats were given two different sweet-flavored liquids. For the first group, both liquids were sweetened with natural high-calorie sweeteners so the relationship between taste and calories was consistent. For the second group, one of the two flavored liquids was artificially sweetened with saccharin, making the relationship between sweet taste and calories inconsistent.
After 10 days, the rats were allowed to eat a sweet, high-calorie, chocolate-flavored snack. The rats that had had the artificially flavored liquid were less able to compensate for the calories in the snack -- at mealtime, they ate more. The animals given artificially sweetened drinks ate about three times as many calories as those that didn't get artificially sweetened drinks, Swithers said.
In the second study, two groups of rats were fed a high-calorie dietary supplement plus their regular food every day for 30 days. The supplements given to each group were the same in calories and nutrition; however, one group's supplement was like thick chocolate pudding while the other was like chocolate milk.
Those given the milk gained more weight than those given the pudding-like supplement, leading the researchers to conclude that the rats were less able to estimate the calories they were eating in liquid foods than semi-solid foods. This may help explain why people who drink regular soft drinks may put on weight, the researchers said.
But the sweetener industry objects to the new research. Artificial sweeteners can play a positive role in weight loss and weight control, although "sweeteners aren't a magic bullet," said Beth Hubrich, a dietitian. She's also associate director of the Calorie Control Council, an international nonprofit association that represents the low-calorie and reduced-fat food and beverage industry. "But they certainly can be a useful tool."
In a formal response to the study, the council noted the small sample size of the research -- 10 rats per group -- and added that the research is "mainly speculative in nature."
"Not all rat studies are applicable to humans," Hubrich said. There is no reason to limit the use of artificial sweeteners, she added. "They've all been thoroughly tested. The Food and Drug Administration has approved them."
Hubrich also pointed to a study published in 1997 in the American Journal of Clinical Nutrition in which researchers found that the use of artificially sweetened foods not only helped with weight loss but also with long-term weight control.
For information on limiting sugar, visit the American Dietetic Association.