Animals—and people—learn to link food sweetness and viscosity with high caloric content. Animal studies in the July International Journal of Obesity suggest that regularly ingesting sugar substitutes or artificially sweetened drinks might reprogram individuals so that they can no longer judge the caloric impact of truly sugary snacks.
In one test, Terry Davidson and Susan Swithers of Purdue University in West Lafayette, Ind., provided adolescent rats with sweet drinks and all of the food they wanted for 10 days. Some animals were given only sugared drinks; the rest received drinks sweetened with saccharin alternating with drinks containing sugar. At the experiment's end, the animals fasted for 12 hours before receiving a 5-calorie chocolate snack, a substantial treat for a young rat.
An hour later, the researchers offered the animals a full meal and tallied calorie consumption during the next 60 minutes. Rats that had gotten only sugared drinks ate