Artificial Sweeteners May Trick the Brain
In the study, published in the July issue of the International Journal of Obesity, two groups of rats were fed either a mix of high-calorie, sugar-sweetened, and low-calorie, artificially sweetened liquids; or sugar-sweetened liquids alone. This was fed to the rats in addition their regular diet. After 10 days, they were offered a high-calorie, chocolate-flavored snack.
The study showed that rats fed the mixed liquids ate more of their regular chow after the sweet snack than those who had been fed sugar-sweetened liquids alone.
Researchers say the results show that the experience of drinking artificially sweetened, low-calorie liquids had damaged the rats' natural ability to compensate for the calories in the snack.
Manipulating Food Can Derail Diets
Health psychologist Daniel C. Stettner, PhD, says damaging the body's natural ability to count calories based on food's sweetness is just one way in which food can be manipulated to change eating habits and contribute to obesity.
"We do more to manipulate food than just add artificial sweeteners. The food industry plays with the sugar, the fat, and the salt," Stettner tells WebMD. "It's like a shell game."
Stettner says that when manufacturers lower the sugar content in foods, they typically increase the fat or the salt content to compensate for any change in how it tastes or feels in the mouth. For example, sugar-free ice creams can be made higher in fat content.
"Sugar-free foods can still be calorie-dense, and that can mess up weight," says Stettner, who specializes in weight issues at Northpointe Health Center in Berkley, Mich.
Stettner says the body's natural calorie counter and sense of balance is also affected by genetics, environment, marketing, and physical activity level, which were not taken into account by this study.
"So many factors contribute to obesity," says Stettner. Although artificial sweeteners may alter the eating behavior of rats, he says the same principle may not necessarily apply to humans.
Swithers says that many types of learning processes translate from rats to humans, but she acknowledges that the loss of the ability to judge the calorie content of sweet foods is probably just one of the contributors to the rise in overweight and obesity.