Artificial sweeteners have always seemed a bit suspect. The idea of a genuinely toothsome sensation that isn't "paid for" in calories and weight gain seems too much like the proverbial free lunch. And over the years, various sweeteners—from saccharin (Sweet'N Low and Nutrasweet) to aspartame (Equal) and sucralose (Splenda)—have been linked to health problems, such as tumors and seizures. So far, however, research has not borne out any of these connections.
But are sweeteners effective? Can they actually help you maintain or lose weight, or do they increase craving for real sugary goodness?
At first glance, the results seem mixed. Obesity, after all, has continued to rise in the age of artificial sweetness. Some studies do link short-term increases in sugar craving to sweeteners, but more find no such connection. And people who use artificial sweeteners tend to be heavier than those who don't forswear sugar. However, this may simply be because heavy people use sugar substitutes to control their weight.
Research published in 2004 in the International Journal of Obesity does point to potential problems. Normally the brain identifies sweetness with calories, like Pavlov's dog linking a bell with food. But when a group of rats regularly drank artificially sweetened fluid, they began to miss the connection. Given the chance, they chowed down on more of a sugary and fattening snack than those rats who'd been enjoying sweet, hi-cal drinks all along. If we apply rat logic to humans, sweeteners just might cause a person to eat more, not less.
Fortunately for those of us with a sweet tooth, the best studies—experiments conducted on humans that test cause and effect by carefully controlling conditions—exonerate sweeteners.
In a study published in the American Journal of Clinical Nutrition in 2002, for example, overweight people drank beverages sweetened either with sugar or with a substitute. Sugars aren't very filling—especially in beverages—so the sugar-sippers ate just as much as the other group and averaged a weight gain of 3.5 pounds, versus a 2-pound weight loss for the sweetener subjects.
The effect of sweeteners in humans may differ from that in the rats in part because people tend to consume low-calorie drinks with high-calorie meals—the old routine of burger, fries, dessert and diet soda. This sends our calorie-counting mechanism the message the sweetener-guzzling rats didn't get: Sweetness comes with calories.
"Unquestionably, artificial sweeteners work," explains David Levitsky, professor of nutrition and psychology at Cornell University. "In experimental studies, when you actually measure what people eat with and without them, total caloric intake goes down with sweeteners."
But he cautions that artificial sweeteners must be substituted for higher calorie foods and drinks, not simply added to what one already eats. Richard Mattes, professor of foods and nutrition at Purdue University, agrees: "They are a useful adjunct to weight management."
Bottom line: Sweeteners work if you use them to replace caloric treats and drinks; fear of sweeteners is probably plain old Puritan fear of unearned pleasure.
