Can Sugar Substitutes Make You Fat? – TIME
Like Pavlov’s dog, trained to salivate at the sound of a bell, animals are similarly trained to anticipate lots of calories when they taste something sweet — in nature, sweet foods are usually loaded with calories. When an animal eats a saccharin-flavored food with no calories, however — disrupting the sweetness and calorie link — the animal tends to eat more and gain more weight, the new study shows.
The sugar-fed rats, for example, showed the expected uptick in core body temperature at mealtime, corresponding to their anticipation of a bolus of calories that they would need to start burning off — a sort of metabolic revving of the energy engines. The saccharin-fed animals, on the other hand, showed no such rise in temperature. “The animals that had the artificial sweetener appear to have a different anticipatory response,” says Susan Swithers, a professor of psychological sciences at Purdue University and a co-author of the study. “They don’t anticipate as many calories arriving.” The net result is a more sluggish metabolism that stores, rather than burns, incoming excess calories.
Though it’s premature to generalize based on animal results that the same phenomena would hold true in people, Swithers says, she notes that other human studies have already shown a similar effect. A University of Texas Health Science Center survey in 2005 found that people who drink diet soft drinks may actually gain weight; in that study, for every can of diet soda people consumed each day, there was a 41% increased risk of being overweight.