The study authors suggest that a sweet taste may cause animals to anticipate the calorie content of food, and eating artificial sweeteners with little or not calories undermines this connection. The result is an energy imbalance that leads to increasing food intake or reducing energy expenditure. The authors also measured changes in the core body temperature of the rats. Normally, when the body gets ready to eat, our metabolic system kicks into gear, raising body temperature.
But when the rats. who were routinely fed saccharin sweetened yogurt, were given a new, sweet tasting, high calorie meal, their core body temperature did not go up as much as the rats who had been fed on yogurt sweetened with glucose. The authors argue that the rats' blunted response to food had the combination effect of making them eat more and making it harder to burn off calories.
Lead researchers, Susan Swithers and Terry Davidson, claim, "The data clearly indicates that consuming a food sweetened with no-calorie saccharin can lead to greater body-weight gain than would consuming the same food sweetened with a high calorie sugar." The authors suggest that other artificial sweeteners like aspartame and sucralose may have a similar effect. They advise that counting calories is still the best way to take control of your weight.