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Maybe that Diet Coke isn’t so toxic after all.
Diet soda has long promised a hit of sweetness without the sugar overload that can fuel weight gain. But sobering research has linked artificial sweeteners to a higher risk of heart attack, stroke and cardiovascular disease.
Now, a landmark new study finds that cracking open a can of diet cola may actually be more beneficial than reaching for the water tap.
Researchers at the University of Liverpool recruited 493 adults who were overweight or obese and randomly assigned them to drink plain water or commercially available diet beverages daily.
The diet drinks contained low- or no-calorie sweeteners, including aspartame, acesulfame potassium (acesulfame-K) and sucralose.
Both groups also participated in a structured behavioral weight-management program, allowing researchers to track how their drink of choice affected their efforts to shed pounds and maintain their weight loss.
By the end of the two-year study, participants in both groups had slimmed down — and kept much of it off.
Those in the diet-beverage group lost an average of about 10.6 pounds, compared with 8.2 pounds among those drinking water.
Water is known to support weight loss by promoting the feeling of fullness and temporarily increasing metabolism.
The difference between the two groups wasn’t statistically significant, though, meaning the researchers couldn’t conclude that diet drinks offered a meaningful weight-loss advantage over water.
The weight loss did appear to hold up after the assisted portion of the program ended.
Waist and hip measurements shrank in both groups, while participants also saw improvements in body composition and several measures of metabolic health.
Sugar intake fell across the board, too, with a slightly bigger drop among those sipping diet beverages.
“For people trying to manage their weight, nonnutritive sweetened beverages offer an effective alternative to sugar-sweetened drinks — and perform equivalently to water over two years,” Professor Jason Halford said in a news release.
The findings add a new twist to the long-running debate over whether artificial sweeteners can actually be helpful for people trying to slim down.
Some scientists have raised concerns that sugar substitutes can interfere with appetite regulation, fuel cravings, disrupt the gut and ultimately make it harder to keep the pounds off.
In one study, researchers found that sucralose triggered greater activity in the hypothalamus — a brain region that helps regulate hunger — than sugar did. The effect was particularly pronounced among people with obesity, who also reported feeling hungrier.
Researchers also observed stronger connections between the hypothalamus and other brain regions involved in motivation and decision-making.
The findings raised questions about whether the artificial sweetener could influence cravings and eating habits.
But the new long-term trial offers a more reassuring picture when it comes to diet soda and weight management.
“These latest findings show that concerns about sweeteners disrupting appetite or causing weight gain are not supported when tested in a rigorous, long-term randomized trial,” said Professor Joanne Harrold, dean of psychology at the University of Liverpool.
The data could also put existing public health guidance under a fresh spotlight.
The World Health Organization, for instance, has advised against relying on nonsugar sweeteners for weight control, citing uncertainty about their long-term benefits and evidence from observational studies.
“This study provides the long-term clinical evidence that has been missing from international discussions,” Halford said. “We hope this evidence informs future WHO guidance and public health policy.”
Across the US, more than 140 million Americans regularly consume artificial sweeteners, often as a way to cut back on sugar.
It’s a worthy goal. The American Heart Association advises that men consume no more than 9 teaspoons of added sugar a day, while women should cap their intake at 6 teaspoons.
Yet the average American consumes roughly 17 teaspoons daily — nearly three times the recommended limit for women and almost twice that for men.
