Diet Sodas Cause Weight Gain? Not so Fast
What the research says about whether diet drinks are culprits, bystanders, or sweet tooth enablers.
Diet Soda Drinkers Who Diet Lose Weight
Popkin cites research, including his own, showing that people who drink artificially sweetened sodas as part of a calorie-restricted diet lose weight. So does Maureen Storey, PhD, who is senior vice president of science policy for the American Beverage Association.
“The current body of available science shows that low-calorie sweeteners -- such as those used in diet soft drinks -- can help reduce calories and aid in maintaining a healthy weight,” Storey tells WebMD.
She points out that the American Diabetes Association and the American Dietetic Association support the use of no-calorie sweeteners to restrict calories and sugar intake.
“Drinking diet beverages alone, however, is not enough to counter overeating -- the only way to maintain a healthy weight is by balancing calories consumed with calories burned.”
Nutrition researcher David L. Katz, MD, who directs the Yale Prevention Research Center, says the research as a whole suggests sugar substitutes and other non-nutritive food substitutes have little impact on weight one way or the other.
“For every study that shows there could be a benefit or harm, there’s another that shows no 'there' there,” Katz tells WebMD.
The Sweet Tooth Hypothesis
Katz agrees that the research linking diet sodas to weight gain is scant and inconclusive. But he's still concerned that artificial sweeteners condition people to want to eat more sweet foods.
“We refer to a ‘sweet tooth,’ not a ‘sugar tooth,’ “ Katz says. “I think that is absolutely right. Our taste buds don’t really differentiate between sweet in sugar and sweet from, say, aspartame. The evidence that this sweet taste is addictive is pretty clear.”
His theoretical concerns are bolstered by 20 years of real-world experience with his patients.
“What I have seen in my patients is that those who drink diet soda are more vulnerable to stealth sugars,” Katz says.
Katz says stealth sugars are those added to processed foods that don’t taste sweet, such as crackers, breads, and pasta sauce. They usually come in the form of high-fructose corn syrup.
Although some commercial pasta sauces contain no added sugars, others contain more than ice cream toppings, Katz says.
“The question is, who prefers marinara sauce with all that high-fructose corn syrup?” Katz says. “The answer is, a person with a sweet tooth.”
In their research review, Popkin and Mattes concede that use of no-calorie sweeteners probably does promote a preference for sweeter-tasting foods. But they conclude that it's not clear whether that affects weight gain -- and they say calorie-free sweeteners could help people control their weight, if used instead of higher-calorie sweeteners.
“But whether they will be used in this way is uncertain,” Popkin and Mattes write.