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Study: Do Artificial Sweeteners Cause Weight Gain?

Reprinted from Eating Disorders Recovery Today
Winter 2008 Volume 6, Number 1
©2008 Gürze Books

Casting doubt on the benefit of low-calorie sweeteners, new research shows that rats on diets containing saccharin gained more weight than rats given sugary food. The study in the journal Behavioral Neuroscience found that the calorie-free artificial sweetener appeared to break the physiological connection between sweet tastes and calories, driving the rats to overeat.

Lyn M. Steffen, an associate professor of epidemiology at the University of Minnesota, who was not involved in the report, said the study offered a possible explanation for the unexpected association between obesity and diet soda found in recent human studies. Researchers have puzzled over whether diet soda is a marker for poor eating habits or diet soda ingredients cause people to gain weight, she said. "This rat study suggests a component of the artificial sweetener may be responsible for the weight gain." Steffen's own research has shown that people who drink diet soda have a higher risk of developing metabolic syndrome—a cluster of symptoms including obesity—than do people who drink regular soda.

Other Interpretations

Another industry group rejected the study, stating, "The causes of obesity are multifactorial." Beth Hubrich, a dietitian with the Calorie Control Council, which represents low- and reduced-calorie food and beverage marketers added, "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."

The number of Americans who consume soda, yogurt, and other products containing sugar-free sweeteners more than doubled to 160 million in 2000 from fewer than 70 million in 1987, according to the report. Over the same period, the incidence of obesity among U.S. adults rose to 30% from 15%.

One interpretation of the trends is that people have been turning to lower-calorie foods to control an increasing problem with weight gain. An alternative interpretation is that artificial sweeteners lead to biological or behavioral changes that cause people to eat more. This possibility is easier to test in rats than in people because scientists can control the animals' diets and measure exactly what they eat, said the study's lead author, Susan E. Swithers, an associate professor of psychological sciences at Purdue University in Indiana.

A controlled study is needed to determine whether sweeteners have the same effect in people as in rats, but some epidemiological studies have been consistent with the findings. The next step would be to determine whether dietary changes could reverse the rats' physiological responses.

—Source: Los Angeles Times